What stands between you and success?

So far I haven't performed as well as I've hoped for in the corporate world (and come to think of it, collegiate life). By performance, I mean doing things like taking initiatives on projects or coming up with innovative ideas on a more consistent basis.

And although I don't think it's true, I'm starting to worry I might be like one of those people who refers to themself as a bad test taker when in actuality they're just not very smart. For now I'd like to believe that I have yet to correctly "position myself for success" and that I still have the potential to excel in the real world. But the question remains, what's held me back up to this point?

My first guess is that it's related to passion, or even just basic interests. To be honest I haven't followed through on either for a long time. I'm not sure when it happened, but at some point learning at school became more about doing what most difficult than what was most interesting. Math over Art. Engineering over Writing. Databases over Web Design. And related to this, another problem is that I haven't committed myself to following thru on newer interests. A lot of things have been only partially attempted, which I think ties to a limiting assumption that the things I'm interested in couldn't turn into viable career options.