I understand that it also help speed up the recovery if one exercises before the operations too. Just don’t overdo it and make oneself too worn down before the surgery as that can have opposite effect possibly.
The day before my transplant surgery, I walked 4 miles. The next day they called and I had my surgery. I was home 5 days later, they said I was doing great.
It took me a lot longer than that to fully recover, of course.