As you become older as a tennis player, your body has taken a lot of punishment. All the stops and starts, changes of direction, sore muscles, and joints start taking a toll on you.
 
What do you do? Quit playing back-to-back days! Allow your body to recover. Start a small stretching program for flexibility, maybe a yoga class or check T.V for yoga programs. Sign up for an aerobics class or start a small hand weights program. Try taking a 30 minute walk twice a week, a bike ride or join a gym and use an elliptical trainer.
 
Cross training can be your best friend. When you are hurting stop playing. Fix what's wrong with you. (ice, heat, etc.)
 
Before you play make sure you warm up longer, slowly stretching muscles. Warm up on the court with your opponent, tapping the ball back and forth from the mid-court. This will not tempt you to run wildly in the deep court warm up. So, if you want to keep playing tennis and enjoying your friendships, start pacing yourself!
 
Good luck on the courts!
 
P.S. When you really can't play anymore because of pain or inability to cover the court, check out Pickle Ball. You can cover the court better, make new friends and still get a good workout while having a good time. (This P.S was added by my wife)