We're forever indebted to the first woman who thought of this, as it's not only a convenient place to put T-shirts when we aren't wearing them, but it also makes for a kicky little skirt. The problem is that, at the gym, this style adds unnecessary bulk that can get in your way. And as Harris says, "You think you're being sly in covering up, but everyone's eyes are automatically drawn to what you're covering up." If you can't part with that extra layer, consider this ingenious T-shirt-wrap, or suit up in a running skirt or skort. They're more streamlined and offer built-in pockets.