30 minute workout?

What to do in my 30 minutes at lunch? I tried to run the other day but changing, running, and then changing again - all in 30 minutes seems like way to much work. I guess it is sort of like having sex with very little foreplay, a quickie, and no cigarette after - and don't forget ALL BY YOURSELF. Well I don't smoke but you get the idea. I think I did actually run for about 20-25 minutes. I did have to go back to work after all sweaty. Maybe I should of stayed at my desk reading a novel eating my lunch and watching it all go to my hips.