I've always felt very awkward doing any kind of exercise; I wasn't a very coordinated kid. So I never feel good about myself when I'm exercising and I usually try not to think about how I look. And, when I look in the mirror, I'm usually pretty horrified. Once in a while, if I'm wearing the right clothes, I'm pleased with what I see, but that's definitely the exception rather than the rule.
The only exception is swimming. I grew up a block from our local pool and literally spent every day there during the summer from the time I was 7 until I was into high school. I swam for fun, took lessons, did swim team (eventually in winter too), lifeguarded, taught swim lessons, etc. etc. Sometimes I spent so much time in the water, I sloshed when I walked

. But because I spent so much time in the water, I'm good at swimming. Not as good as someone who swims competitively, but better than the average person. It's the only sport where I feel like I have an advantage and where I feel graceful and coordinated, instead of klutzy and stupid. So, in my mind, when I am swimming, I look like an olympic swimmer. Streamlined, perfect form, and fast. Now, I know I have some form issues, so I'm sure the reality of what I look like swimming is very different from the picture in my mind. But, in my mind, I look fantastic.