Mirror Walls

Last Wednesday, I went to the gym.  I have been to this location about 3 times previously, however I've never noticed this before...

Why are there mirrored walls at every gym?  Is it because people who work out are vain?  They like to look at themselves as much as they can?  Why do people look at themselves when working out? 

I understand that it may help when using free weights because you want to make sure you're doing it correctly...but what about the main gym floor?  Why would one want to look at themselves while running on the treadmill, elliptical or stationary bike? 

On this evening, I wanted to use the crossramp elliptical.  Guess where it was?  RIGHT infront of the mirror.  No joke.  RIGHT infront.  My face was about a foot away from the mirror.  The swinging arm stick was centimeters away from hitting the mirror.  Because I was so close to the wall, I had no televisions or asses to look at.  So what did I do?  I stared at the people working out behind me.  How often can you say you've done that, eh?  I didn't enjoy looking at people through the mirror because it's really awkward when you make eye contact...through the mirror.  However, it WAS better than starring at myself the entire time.