Which Gossip Girl Said, "Just Do It"?

We've talked about Blake Lively a few times here at That's Fit, but she's not the one who just completed a bad ass Nike ad. That honor goes to Taylor Momsen.

Momsen, known as "Little J" to her legions of Gossip Girl fans, doesn't exactly play a sporty character. She's more into short hemlines, massive amounts of eyeliner, and unfortunate haircuts. However, in real life (well, in a Nike commercial, anyway), she's beyond sporty -- she's practically a superhero.

After this, I wouldn't be surprised to see more paparazzi-prone starlets lacing up their sneaks when exiting Hollywood hotspots. It could be a new form of celebrity fitness -- 'razzi racing!