Use it as motivation. I think one of the reasons I was successful was because I didn't make the Little League All Star Team in my town. All my friends were on it. Not me. I was 1) embarrassed, 2) ticked off, 3) motivated to be better than every single player on that team.
The next season, I didn't make a well-regarded summer travel team (was cut in tryouts). Again, I was motivated to work harder than anyone else ... to prove them wrong.
Bottom line: you've got to believe in yourself and then go to work. By the time I was 15, I was a freshman #2 starter on my varsity baseball team and went 6-0. We finished third in the NY State finals. Probably wouldn't have happened if I hadn't been cut at 12, and 13.
Different scenario than your injury? Yes. But same underlying principles apply.