I was practicing sports from 10 to 17 years old , then I gave up, smoke a lot. Did almost nothing related with sports. Only from 35 I started again seriously. When I started first with light racquet Head TI S.6 I got wrist problem, I couldn't lift up a kettle. Then I shifted to i.Prestige Mid. After 4 years of practicing ( 3 times a week per 1 hour each) recently I shifted to PS Tour 90 because of elbow problem. My elbow sometimes hurts me a little, despite I make also very short exercises with dudmb-bells every-day. Somewhen 2 years ago I felt a weakness in my knee. It reminds about itslef very rare, but reminds say once in 3 months. I'm 39. Of course, I love tennis and can't imagine life without it. But all these rise the question is it helthy sport, is it worth to practice with? Isn't it also bad for heart and for lungs ?