Use it or lose it is powerfully correct. But in order to use it, it is important that all the mechanical imperatives are obeyed. Our longtime shared running goal is to run until we are 100 with or without our original hardware. Remember that the devil can't hit a moving target.
"It's a terrible problem," she said, "They can't exercise without pain before the operation, but if they don't lose weight, their new knee or hip will wear out and they may develop other orthopedic problems."