Yes! I played as a teenager and into adulthood. Great excersize!! A CFer should do as much activity they can without feeling too sick/out of breath from it. Excersize, when doing it correctly and appropriatly, cannot hurt.
Yeah, I love to play tennis. this game was too good and most energy consume in such games. Especially i think your stamina was too much matter in this game. I am fan of Roger federer. He is playing very well and fantastic stamina he have.