From the history in your question, it seems that your surgeon has given you appropriate post-operative instructions; that is, that you can return to work in 6 weeks. I generally allow patients to begin upper body exercises at 3 weeks and instruct them to increase gradually over weeks 4-6 until they reach their preoperative level. If there is any discomfort at all, I advise them to stop or reduce the level and frequency of their exercise for a period of time. Having said that, subpectoral implants do change the interface or gliding plane between the pectoralis muscle and the chest wall. In most patients this does not make a difference, but there is an occasional patient who always experiences some awareness of a change when the pectoralis muscle is contracted.