The first and most important word you learn is 'no'. As in "No, this is not what I want." Maybe we don't always know what we DO want, but that doesn't mean we have to stick with what we DON'T. Humans are adaptable, we alone can change our situations. 'Better the devil you know' is not an acceptable answer.
As for 'how do I know what is right'? It's not a question of which path takes you to where you want to go, it's a question of which takes you away from what you don't. Life is a journey, not a destination; never stop traveling or experiencing.
I'm not gonna ramble on too far explaining this...I think it's pretty clear. Life is easy, it's people that make it hard. You really can do anything you want to do, you just have to be willing to work for it...scratch that: you have to be willing to work for YOU.