Well... you don't say who it is you imagine you could be if you weren't busy being someone else because of the people in your life. I've had a lifetime's worth of experience with this. And I'm here to tell you it's not pretty!

Anyway, in terms of advice on how to change, assuming that the things you want to change don't involve your basic "personality structure" so to speak, but rather involve such things as how you spend your time, what you eat & / or drink, who your friends are... that sort of stuff... then the advice I would offer would be to simply start small with one or two things that aren't too difficult. Then go on from there adding a few things as time goes on.

Trying to make wholesale changes seldom works in my experience. It's just too much too fast. And then, going along with that, you may need to make some additional changes with regard to the people you spend time with & where you "hang out". You can't expect to continue to be surrounded by the same people & temptations that caused you to become someone you don't want to be & still change I don't believe. Change can be difficult. But you can do it.