I played baseball competitively from ages 6-15 and currently play tennis at the varsity level in high school. I've played enough basketball and football recreationally so that I don't embarrass myself when playing a pickup game.
I am a huge baseball fan and I watch hundreds of games each season, devoting several hours a day to reading about and watching it. I watch tennis as well, but only the Grand Slams and other big tournaments such as Indian Wells. I watch basketball and football casually during the fall and winter.