Most people think being intelligent or whatever it is - decided by genetics but this isn't strictly true. You can actually reshape the physical structure of your brain through specific training exercises and audios. see that’s cool.
Just like training a muscle in the gym, you have to be persistent. Although training your brain is far more rewarding. yeah! Beast mode!!

Become a student for rest of life.
Be a student of life—not just wealth, health and happiness. Study history, science, psychology, art, languages, math, music, etc. Learn how this world works. Add depth to your mind and character(this one is important: Character).
It will improve your working memory, and one study showed it true. (cheers)
Do regular high cardio exercise.
try some, see difference. no words so far.
Learning to play music is the equivalent of giving your brain a full body workout. This has been proven in studies using FMRI scans.
Experiment ! wondering how music relates intelligence.
Go up into the hills and find a hillbilly who can't multiply fifteen and two and but can light a fiddle or banjo on fire. Teach him how to multiply fifteen and two and see how long it takes till he's teaching you math. If you can't read music, you need to improvise, which requires abstract thought, which is a cornerstone of intelligence. Don't confuse knowledge with intelligence.
Albert Einstein quotes.
"Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution."
Buy the book, try to Read a book a week.
This is one is really important, friend! Read a book- i mean not god damn textbook. It doesn't mean skip your textbook. You read all thatinspire you, that will make you jump out of bed every morning. study study study. google reasons why to read books. See 5 Ways to Read More Books .
write answer in Quora, start blogging(kind of).
phew! yes! you hear right! This certainly will help you thinking, learning new things, explore, overcome challenges many more.
It's worth checking out Roadmap to Genius [1]which contains all the best known exercises to significantly increase your intelligence