Start exercising more and more man, take it easy at first and keep going to the gym, even if its just to walk on the treadmil.
Start doing some weights for your upper and lower body too. I am a firm beleiver that exercise will make a person stronger mentally and physically.
I broke 3 vertabrae in my back years ago and the doctors told me Ill never be able to lift anything heavy. Wanted to start me off on meds and therapy.
I was back in the gym 2 months later, and my back is stronger then ever, I am able to pull 400+lbs off the ground easily.