there's a lot of self awareness in this question.
it implies the author feels they wasted 8 years (after high school) or 4-5 years (after university) but are now ready to up their game. good!
thing is, i'd argue most people don't tap into their life's work until their late 20s or even later. a few examples:
not to mention, your early 20s can be salvaged. the experiences (good or bad) and jobs and mistakes can be turned into content for your life's work.
were you arrested? write about how going to jail changed your life. and on and on.