The Secret To A Better Workout?

So I'm getting ready to go running on my treadmill but I couldn't find the shirt I usually work out in, so I decided I'd just do it without a shirt because it was already hot. I get about a half-mile done and then I realize that I can see myself in my mirror, and I instantly go "Oh god is that what I look like with my shirt off?!"

I'm pretty sure I found a sure-fire way to make you workout harder, and for a longer duration. Just seeing what I looked like now was a perfect tool in motivating me to keep doing what I'm doing, and I ended up working out for nearly twice as long as I usually do. So all you need is a mirror in front of you when you're working out and then you'll never want to quit :)

Anyone else have some weird workout tips they've stumbled upon?