I've finally gotten back into going to the gym on a regular basis, and as I did some rollerblading around campus today, I noticed more girls looking at me. Now, I don't work out solely for that reason, but it is a nice bonus. What I finally realized is that people in general give more respect to someone who has some muscles. It's usually a fairly subtle effect, but it is extremely pervasive.
My dad convinced me to go the YMCA with him one day, and after I stepped outside again, tired and sore, I felt a lot better. That feeling has kept me going back pretty much every other day for the last three years. Before that, I used to think that bodybuilders and the like were just egotistic and stupid, and while that's true of a few, most people think of a toned body as a mark of self-respect. Your body reflects the state of your mind in many ways. Some people, when they're nervous, chew their fingernails. Shy people will probably tend to hunch over a bit. So when you take the time to excercise, it shows that you care about your body, and you're not going to let it go unmaintained. It shows that you have confidence and self-respect.
How much time do you spend doing system administration on your GNU/Linux or BSD machine? How long did it take you to set up RAID 5, upgrade your kernel, or to install the latest version of GNOME 2? Don't you think you should spend at least a fraction of that time (e.g. an hour every few days) doing "system administration" on your body, which keeps you alive? So stop reading this, and go apply for a membership at your local gym. You'll be glad you did.