I am in my early 40s. I have played tennis since I was real young and I play 4.5. Recently I have been playing a lot. For me that means 3 days in a row of playing 2.5 hours of hard workouts. Sometimes my strength in my arm seems to go. I get where it is hard to hit a shot in the court with my forehand. My serve still has plenty of pop and my two handed backhand is fine but the forehand.... It is weak to the point that I can hardly form a correct shot. This happens after playing an hour or more. I figure that I need rest and it is probably from being out of shape and then playing too much. What would be some good exercises to do to help this condition?