I never played tennis for fitness. I was in much better shape when I played basketball recreationally. High intensity pick up basketball is a better workout than anything other than a really hard core non-stop hitting session.
I always loved tennis but made it more of my main pass time after injuries from basketball piled up...twisted ankles and jammed fingers being the real deal breakers, I just couldn't deal with them anymore.
So, I play tennis because I love it. I wish I could get more cardio out of my league matches but there are too many out of shape guys in the league who wouldn't allow that to happen.
3.5 player. Equipment: Prince Original Graphite OS, Tourna Big Hitter Blue