I believe I tore my rotator cuff about three times doing martial arts. The first time it pretty much healed on it's own and I could do pushups again after nine months. The second time it was a year before I could do them and then I completely tore it doing incline pushups. By the time I went to the doctor, he told me that it had been too long since the injury and the rotator cuff was un-recoverable.
I had a total reverse shoulder replacement in May of last year.
Since then I have gone back to pushups and am doing 100 a morning before going to work. I started slow at about six weeks after the surgery (slow, like two a day the first week). The doctor was not particularly pleased at the two month checkup when I told him I was doing pushups, but it has been my experience that doctors will almost always underestimate or understate recovery capacity.
Discipline is just choosing between what you want now and what you want most.
Gunsite Orange, API -250 Sept. 78 (Everybody starts somewhere)
CRG - July 11
PSP - April 12
TMCO - Sept. 12
TWOTU since 2011
Glock Certified Armorer