If you read some materials about personal development or success or marketing (and probably many other areas, but not as prominent), these words usually come as an axiom:
Consistency is [the] key.
It doesn't say to what is the key, but from the context we generally assume it's the key to success or to personal development, or to better marketing results.
Some people are rarely consistent in anything. We can probably say they are consistently inconsistent. Which, if we apply the axiom above with a mathematical rigor, that would make them a success, eventually. But in life, that's a maybe, at most.
The majority of people are consistent about something, at least for a while.
Helen has a passion for photography. She often takes professional photographs. The more she does it, the more techniques she learns, the steadier the hand, the greater the details or more filled with life and emotion the moments captured by her camera. And, of course, she improves her equipment as she gets better too.
George needs to lose a few kilos. He decides to run for half-an-hour every morning and work out for an hour twice a week. It's very hard at first to keep up with his schedule, but he's determined and never misses a day of running or a session of workout. After 6 months he meets a friend who is impressed by how fit he looks, and asks for the wonder solution. George tells him what he did, but his friend wasn't very convinced to commit to such a schedule.
Allen is a teenager and he plays hours of video games with his mates. One day when he was playing alone, his dad passed by his room and stopped, starting to build up a bit of a temper and wanting to intervene firmly. But then he remembered he used to play some video games too when he was a boy and liking them, and cooled down a bit. As he entered Allen's room, he asked him to show him what else is he good at besides games, or he will restrict his access to his console. Without pausing his game, Allen pointed out a big notebook on the desk. His dad took it, opened it up, and to his surprise found many good or great sketches and drawings, some finished, some not. Yours? he asked. The boy nodded, and his father said These look great son!, as he leaved the room satisfied.
Eva wanted to look great all her life. Much to her dismay, she has a very slow metabolism and every bit of food she eats seems to show on her body, unlike her awesome looking friends. She started to eat less and less, always calculating calories, until she finally modeled a body everyone envied. Except... she didn't stop. Ate less and less until people started wondering if she ever ate and finally some close friends started worrying and she ended up in the hospital.
Joe had a tough life. He learned to lie, cheat or steal early on. As time flew by, he got better at it. He also got caught and did time. He associated with the bad kind of people, and if you would have met him alone on a dark alley, you wouldn't have crossed on the other side, you would have turned around and ran. Now he's at midpoint in his life. That's all he knows and respects. If he'd want to change, could he? Would he? And what would it take for you to believe it?
Consistency is not the key. Consistency is deceiving. You think you can control it, but it controls you, because it starts slow, without noticeable changes.
What you can control is what you are consistent about. The actions you turn into habits. So take control over them!