I've talked on here about limiting beliefs and accepting failure or obstacles as impassable or impossible.
As difficult as it is, you have to decide if and when you let a circumstance determine how far you think you can and thus how far you are actually able to go.
I found a way to train through 9 months without an ACL and win Judo and Brazilian Jiu-Jitsu matches in competition. Advisable? No. Possible? Yes.
That being said...the following are two people well acquainted with proving the doubting Thomas' of the world woefully incorrect.
Exhibit A: one armed MMA fighter
Exhibit B: one legged wrestler