I have a pretty big ego, but I do realize my limitations. I know that there are some things I am incapable of, and they are:
-Martial arts - I lack the balance and discipline.
-Breakdancing - No coordination. The same goes for all dancing.
-Orienteering - Even with a GPS I can barely find my way around a grid of streets, and when I'm playing a video game without a flashing indicator that tells me where to go I'm screwed.
-Pretty much anything athletic. There was a time I could hang on the basketball court, but I gave up playing when it became obvious to me my future was not in the NBA. I'm OK at skill games like tennis, racquetball and whatnot -- sports that reward you for being quick enough to pretty much stay in the same spot if you have enough skill.
-Standing for more than a couple minutes. I've got a bad back that requires me not only to sit whenever possible, but to be able to lean back against a surface. If there's not constant pressure on my spine, it starts to ache. I've had it checked out and the doctors can't find anything wrong with it.
-Doing anything with my hands other than typing. I cannot fix, weld, construct, deconstruct, repair, cook or modify anything. Mostly because I have no interest in learning how to do any of those things. If I lived in the days of cavemen or frontiersmen, I would have had no chance of survival.
-Fighting. I don't have enough experience and can hardly ever channel the requisite rage. I haven't lifted weights in more than 10 years. If you are a comparable size to me, you are going to win. So I am going to throw dirt in your face and run. The problem with that is I'm pretty slow, so you'll probably be able to chase me down.
-Shooting. I am terrified of guns and will never own one. So add that to the lack of fighting ability and I've got no chance of withstanding any sort of violent confrontation.
That about wraps it up. After reading all that, you might wonder what it is I can do. The answer is not a whole heck of a lot, but because I'm so aware of what I can't do, I play to my strengths, stay out of situations that exploit my weaknesses and spend a lot of my time sitting and writing, watching movies or playing video games. Luckily for me, I live in a time when it's possible to do that, make enough money to feed a family of four and still feel damn good about yourself. So I win.