I play racquetball 3 to 4 times a week, it's fun and a great work out.
I find that if I maintain a conditioning exercise plan along with my RB, my game by far is more effective.
Three times a week I do cardio on a machine, like an ecliptic, and then I do some very light weights--just for toning and strength.
Stretching is important too. There are some wonderful stretches that are quick and easy.