Yes, there is a gym upstairs and yes, that's why I'm wearing this

One of the nice things about my job is that our company keeps a low-key gym on another floor in our office building. Since I mostly just snack at my desk throughout the day, I use my lunch break to go upstairs to run (and to watch Seinfeld). I try not to go before about 3:00, so that I am not walking around the office all day in my gym clothes -- but the few hours I am in my running gear are usually uncomfortable.

Obviously my co-workers all know that I show up in normal office wear, and change only when I'm headed for a workout. But as soon as I step out into the hall, I've noticed that other people on our floor who see me in passing or in the bathroom give me blatantly disapproving looks. It's pretty obvious that they all think I am just wearing shorts and Nikes for the hell of it -- as if I assumed a messy ponytail and a track T-shirt were the hallmarks of appropriate professional attire. Several of them pose the awkward question: "So ... are you going to the gym later?" without ever having met me.

I assure them that there is a gym right upstairs, and I use it on my lunch break, which usually elicits a relieved nod. For some reason, perhaps as more and more people give me confused glances ("I can't believe she shows up to work in that"), I've become really bothered by it. I find myself wanting to blurt out "yes, there is a gym upstairs and yes, that's why I'm wearing this," to anyone I encounter between my office and the elevator. Or perhaps, if I get increasingly aggitated, I could try the less subtle but equally effective "there's a reason why my ass looks so much better than yours, and it's because I go work out every day, like I am about to do right now." We'll see how it goes.