Here's a mental image for ya:
I just did 45 minutes of Billy Blank's Boot Camp. (I would have done a whole hour, but I accidentally stepped on the "Eject DVD" button, and I was down to only doing about 1/5 of each exercise because of muscle fatigue. So, I stopped at 45 minutes.)
Why the mental image?
Because all I'm wearing is boxer briefs, tube socks pulled up to my knees, and these shoes: