I set up my stationary trainer (resistance mount for the rear wheel of any of my bicycles) in my apartment, and jump on it every hour or two during my work-at-home days. I ride only as long as I feel comfortable not sitting -- just standing cycling.

I may sit for a few moments, or depending on my condition even up to half of the session, which lasts anywhere from a few minutes, to 15-20+....I stay in a gear that supports my weight but doesn't leave me breatheless, and keep the pedals spinning as long as I can.

The convenience of having a cycling setup just a few feet away from my workstation, allows me to get plenty of exercise time during the day -- without putting wear and tear on my prostate.

Form-fitting but not too-tight boxer briefs and shorts are a good idea for this. During the winter, I try to keep my metabolism high enough that I can wear shorts and a t-shirt indoors comfortably during the day :-)