You

Ever tried to do more than you knew you could?
Yeah, I'm right there with you. Guilty as charged. Sometimes any limitation I have feels like something to just ignore. It's like when you were a kid, and the definition of "cleaning your room" was taking all of your possessions and shoving them under the bed.
A recent observation of mine is that I as a Soldier am very prone to the thing I like to call I-wish-I-were-normal-itis. Seventh grade track, learning theater choreography, or even wearing glasses, I wished I was normal.
Sorry to burst your normal bubble, but I've got a newsflash. Exhibit A, who said normal existed anyway? My parents may not be traditionally disabled, and yet my mom takes thyroid medication and my dad complains of a herniated disc. Even outside physical health this is apparent. To be normal is to have a few quirks. Heck, I rock out to Shania Twain in my bedroom, and I still have my stuffed teddy bear I received back in the ICU. Out. Clearly visible in my room. Not shoved in the corner of my closet.
See? We're all weird.
Exhibit B: I don't think when you say "normal," you mean normal. What you actually mean is "I wish I had what they had."
Full disclosure, this is not putting down feelings of being different. Not being able to go out for sports in the traditional sense because you're wheelchair-bound sucks. Period.
But sometimes in my experience I would say I wished I were normal when I was missing the value in my own talents. The cool gymnastics girl, people more advanced than me in equestrian sports, people with really nice handwriting, those are all examples.
Sometimes you just have to accept you for you. My life coach calls it "radical acceptance." You accept the reality you're in, and that's the way it is. You adapt instead of getting caught up in your own musings.
Yes, I wish I could get my math homework done in fifteen minutes, but let's face it, my ADD means it'll take me an hour. So I prepare for that, I make allotments in my schedule, and life goes on. And what everyone else can do in math, well, that's not my strength. But I can CRUSH in debate.
Remember your strengths when you're out of your element. Adapt to your weaknesses, and your strong points will show all the more.
The first step is acceptance over wishing and comparison.
To be a little more frank: You are you. Deal with it.