1) A no-schit barbell (one that'll spin so you can do cleans). Also required are stains on the bar from where your hands have been in the proper locations...a lot. Rubber bumpers instead of iron.

2) Squat rack so you can do pullups and barbell work, IE SQUATS

3) The Crossfit site saved on your computer.

4) The desire to make it happen

A lot of you guys suggested a lot of good stuff, but no one offered all the pieces of the puzzle. Honorable Mention goes to Tanner because he is correct about short hard runs being more effective for general fitness than "jogging", though.