Well as far as the main operation is concerned you could do any thing or even more than what you did before operation. As regards to your scar, I believe it was done through an open surgery. In that case you should be careful of developing a weakness of the scar (incisional hernia). Though 3-4 months after surgery nothing should happen but consult a physiotherapist and he will tell you which exercises you should not do. But you must exercise to strengthen your muscles and burn your fat.