I once heard a saying "in your teens you think you know everything, in your twenties you are trying everything and you spend your thirties cleaning up your twenties." Do you think thats true?

No I don't.

I never had to clean up my life.

Seems pretty accurate to me. 😉

It sounds clever, though not especially accurate in all cases. 

For me, in my teens, I became acutely aware of how much I really didn't know; 

spent my twenties in awe of that deficit, and set about learning to fill the breach; 

in my thirties, I came to understand that there is a limit to what can be known or done in a single lifetime.

In my forties, I resolved to strain that limit...

could be for some, but not for me

I'm only 21, but the way things are going, that is very true :P