I turned around what I was spending energy on and just "accepted" what other people said/saw and started looking to see if they were correct instead of "not believing." I doubt you have any "evidence" to saying you're not smart? They probably do have evidence that you are, they're looking at you from the "outside" so only see "real" things? Get very literal like that; you're going to college, you have to have a certain amount of smarts?

I love asking my husband what he sees my strengths as because he's very "flattering" and specific and I know I trust his judgement (so can trust it here, too, even if I don't "see" it yet) so I work with what he says and try to see specifics. If one is looking for good things instead of "denying" them or worrying about belief/no belief, one's perspective and orientation changes. Looking at/for good, happy things; you will literally see/find those types of things. What can you find with disbelief?

Were I you I would start by just suspending my disbelief as irrelevant? I'd find some one simple thing someone specific has commented on, "I like you" or "You're smart/sweet/kind/a hard worker, etc." and look for what the other person sees. I'll bet you'll find it and that will make you think better of yourself :-)