Lewandowski came from a sporting family. His mother Iwona played volleyball for Poland, while his father Krzysztof played football outside the Polish top flight with Hutnik Warsaw as well as being a junior European champion in judo. Both worked as physical education teachers.
"He knew we were going to raise a footballer," Iwona told The Blizzard magazine, when discussing Krzysztof's influence on his son. "That's why he is Robert. Travelling through Europe, Krzysztof witnessed how important it would be to have an internationally recognisable name."
Lewandowski grew up in Leszno near Warsaw, and at school he dabbled in the sports his parents excelled in as well as athletics, basketball, and handball. As a boy he travelled to the capital to play with Varsovia Warsaw, where he began training with children two years older than him.
Lewandowski is a well-built 6ft tall forward now, but he was conspicuous for other reasons as a child. "I remember him as the smallest, skinniest boy," his first coach Marek Siwecki told World Soccer magazine. "His legs looked like two thin sticks."
Kamil Baczek, a former teammate of Lewandowski's at Varsovia, told a similar story.
"You can't imagine how small and skinny he was as a child", Baczek told 51, the official Bayern Munich magazine. "You almost had to worry about something happening to him. But he was an outstanding player - he took on every opponent mercilessly."
"I was small, short and very skinny," Lewandowski himself recalled. "Everyone said 'you are too small, you won't make it.' But I wasn't going to give up."
Several of his former coaches at youth level describe how the ball "loved" Lewandowski, and his knack of finding himself in scoring positions would not desert him.
Potential can only get you so far, however, and Poland's record goalscorer overcame some serious setbacks on his way to the top. His father, who spent long hours driving him to and from Varsovia, would never get to see him play professionally. Krzysztof passed away from illness in March 2005, when his son was only 16.
"The memory of my father still drives me on," Lewandowski later told SportBild while he was at Borussia Dortmund. "When I do extra training, I tell myself 'I am doing this for him' and that is good motivation."
His next move was to fourth-tier side Delta Warsaw, but he swiftly linked up with the reserve side of current Polish champions Legia Warsaw. In his one year there he was out for three months with a knee injury - one of very few that he had in his career - and Legia released him in June 2006. Aged 17 at the time, Lewandowski was devastated.
"It was one of the worst days of my life," he wrote in The Players' Tribune. "Now my career was falling apart." His mother, however, enlisted the help of one of his former coaches and within hours he was training at third-division Znicz Pruszkow.
From there, Lewandowski rarely looked back. Ex-teammate Zbigniew Kowalski told World Soccer that - unlike most young players - Lewandowksi didn’t think he knew better than the coaches. Another characteristic was that once he fulfilled one ambition, he'd immediately set another goal.
Goals, of course, have become Lewandowski's calling card. He scored 15 of them in his first year with Znicz, topping the scoring charts and helping his side earn promotion. The following season, he bagged 21 goals to finish as the leading scorer in the second division. He had his pick of Polish top-flight clubs after that, choosing to join Lech Poznan in the summer of 2008.
Lewandowski scored with a backheel on his league debut, and in September of that year - shortly before his 20th birthday - he earned his first cap for his country. The substitute got on the scoresheet, too, in a 2-0 win over San Marino. Poland coach Leo Beenhakker said after the game that the debutant was "perfect" mentally, someone who knew exactly what he wanted from the game.
Goals and - increasingly - silverware seemed to be what Lewandowski had in mind. He won the Polish Cup and Supercup with Lech in 2009 and fired them to the league title in 2009/10. Naturally enough, he finished as the topscorer in that season's Ekstraklasa as well.
By the summer of 2010, after 41 goals and 20 assists in 82 matches for Lech, it was time to move on again. Dortmund were interested, but so too were English Premier League side Blackburn Rovers.
Rovers boss Sam Allardyce travelled to Poznan to see Lewandowski in action, and Martyn Glover, the club's head of recruitment at the time, later told Sky Sports that talks with the Lech president went well.
"After that, whatever could have gone wrong went wrong," Glover recalled. A trip to Manchester airport had been booked, but a volcano eruption in Iceland and the ash cloud it created caused flights to be cancelled throughout Europe for weeks.
"I wanted to go there just to see what the club is like because I didn't know back then where I was going," Lewandowski told ESPNFC in 2017 when discussing his planned visit to Ewood Park.
"I couldn't go but I have to say at that time Blackburn was my second choice anyway. But maybe if I went there and saw the club - the stadium and everything - it would have become my first choice."
Having joined Dortmund before his 22nd birthday, Lewandowski was part of an exciting young side that stormed to the title under Jürgen Klöpp in 2010/11. BVB's Polish attacker scored eight league goals in his first season in the Bundesliga, starting with a header in a Revierderby success against Schalke and ending in the title-clinching home win over Nuremberg.
"The first two years at Dortmund, my finishing was not like it is now," Lewandowski told the BBC in 2019. "After every single training session I stayed on the pitch and practiced with my left, my right foot, and being systematic and repeating the movements was very important."
Lewandowski probably owes Klopp a little for his current goalscoring exploits. The player tells a story about how his coach made a bet with him early on. If he scored 10 goals in training, Klopp would give him €50. If not, the player would have to cough up. The first few weeks were costly for Lewandowski but after a couple of months the tables turned.
Lewandowski had played behind the striker as a No.10 in his first season, and in 2011/12 he felt he was still struggling to impose himself. A turning point, he says, is when he had a heart-to-heart with Klopp about what was required of him. Reassured by the empathy his coach showed him, three days later - in October 2011 - Lewandowski scored three goals and made another in a 4-0 victory over Augsburg.
"At the time I didn't think about it." he wrote in The Players’ Tribune. "But now I realise that my conversation with Jürgen was like one of those I wish I could’ve had with my dad."
Comparing Klopp to a teacher who wanted "A+ students", he credits the current Liverpool boss with pushing him to improve. Lewandowski became increasingly influential, scoring 22 times in the league as Dortmund held off Bayern in a thrilling title race, before delivering a stunning hat-trick as they beat the same side 5-2 in the DFB Cup final.
By his mid 20s, Lewandowski was unrecognisable from the somewhat scrawny teenager that had started out. His former Dortmund teammate Nuri Sahin nicknamed him "The Body", saying the forward was just "pure muscles."
Lewandowski said he focused on diet and gym work to gain an advantage on the pitch, something that was clearly paying off by the 2012/13 season - when he scored 10 goals in the UEFA Champions League.
Four of them came in a 4-1 drubbing of Real Madrid, the first time a player had ever scored that many in a Champions League semi-final. Dortmund came up short in an all-German decider against Bayern at Wembley, but Lewandowski was now a bona fide world star.
He served the last year of his contract at Dortmund, finishing as the Bundesliga's top goalscorer for the first time in his career. He had registered 74 goals in 131 Bundesliga matches for BVB - and 103 in all competitions - by the time he left for Bayern in July 2014.
Lewandowski netted 25 goals across all competitions in his first year in Munich, but his numbers improved along with his all-round game. In Pep Guardiola's final campaign with Bayern, Lewandowski became the Bundesliga's top goalscorer for a second time - hitting 30 league goals in a season for the first time.
Guardiola, who was as amazed as anyone to see the Pole hit a record-breaking five goals in nine minutes against Wolfsburg in September 2015, said the Bayern star's dedication was unrivalled.
"He is the most professional player I have ever met," the current Manchester City boss said in February 2016. "In his head, he thinks about the right food, sleep and training: 24 hours a day. He is always there - never injured - because he focuses on these things. He always knows what is important to be in the best condition."
"There is no team in the world he wouldn't improve," said former Bayern player Didi Hamann later that year, after Lewandowski had agreed to extend his stay in Bavaria.
In 2016/17 he scored 30 league goals again, 29 the year after that, and in 2018/19 he topped the Bundesliga scoring charts for a fourth time.
In 2019/20 he reached new heights, registering 55 goals in all competitions. He helped Bayern to a league and cup double, but also got 15 goals in the Champions League to become a European champion for the first time.
"Never stop dreaming," Lewandowski advised on Twitter afterwards. "Never give up when you fail. Work hard to achieve your goal."
He later helped Bayern win the DFL Supercup and the UEFA Supercup, and in February 2021 the record German champions completed a remarkable sextuple of trophies when they beat Tigres in the FIFA Club World Cup final.
The Poland captain was unsurprisingly named as the world's best player in 2020, but there was no danger that the 32-year-old would settle for that. In May 2021, he broke a record that had stood for almost 50 years.
Bayern legend Gerd Müller had got 40 goals in 1971/72 but - with a penalty in the 2-2 draw with Freiburg - Lewandowski matched Müller's piece of history. The Bayern No. 9 had one last chance to improve his tally on the final day and - ever the showman - he left it until virtually the last kick of the campaign to get his 41st goal of an unforgettable season. That strike in a win over Augsburg has set a new benchmark that is unlikely to be beaten anytime soon.
Lewandowski's transformation is an example of where willpower can get you. He's gone from a slight and slender youngster to a strong and sharp striker. He's now a deadly finisher off either foot, good in the air, hard to shake off the ball, a penalty specialist, and a capable free-kick taker. Throw in an admirable work rate, a team ethos, and his defensive efforts and you have - according to the likes of Germany greats Jürgen Klinsmann and Lothar Matthäus - the complete player.
Not everything came easily to Lewandowski, particularly from the age of 16 until he established himself at Dortmund. He says that perhaps helped him to develop the hardened mentality required to make it as a professional, and also the desire to make the most of his ability.
"Everyone has talent - some more than others," he told GQ. "But you can't achieve anything without really hard work."
What also marks Lewandowski out, however, is his staying power. He has spoken of admiring Roberto Baggio, Alessandro del Piero and Thierry Henry while he went from being a wide-eyed child to a budding professional. A more recent inspiration, though, has been evergreen tennis star Roger Federer. Shortly after turning 32 last year, Lewandowski told kicker that he felt "better than I did at 26", and he revealed in GQ more recently that he wants to play for at least another five years.
With over 200 league goals for Bayern and closing in on 300 in total, the next major target for the Pole is to surpass Gerd Müller's career record of 365 Bundesliga goals in the all-time ranking. Third on the all-time list for goalscorers in the Champions League - 73 and counting by the end of 2020/21 - he will also be dreaming of becoming a European champion again.
And having come this far, who would bet against the six-time Bundesliga top goalscorer hitting those targets?
"Getting to the top is one thing, staying there is another," Lewandowski told GQ in April 2021.