Interesting question. I think about this sometimes. If we're willing to take the consequences, we can technically do whatever we please, but we are limited to the options we can think of and comprehend, analysed by our imperfect thought processes (I might not realise that certain options are available, or may not believe I'm capable); and we are limited by what we consider unacceptable consequences (losing home, jail, disapproval).
I have no idea how much a person can change their basic attitudes and beliefs, or how much real control they have over what they choose to do (or don't choose - I feel like a lot of what I do is the default, me with the absence of having made a choice). But I'd agree with HopefullyLost about trying the more optimistic path. I know that the pessimistic one gets you nowhere new. Even if our destiny is mapped out, being active in making our future might be enough to give a sense of purpose or satisfaction.
Sorry for the rambling.