Kim Kardashian has been working hard to get her body in tip-top shape, and on Thursday, the 37-year-old reality TV star was spotted exercising on the beach in LA with her friends. The ladies did some yoga and went for a short run, and they must have worked up a sweat because they then proceeded to strip down to their bikinis. Kim, of course, looked incredible in a sexy gray two-piece while her friends donned similar suits. Given that Kim is a fan of National Nude Day, which is this Saturday, it's possible that she just wanted to make sure she looked especially good for her selfie this year. Guess we'll just have to wait until the weekend to find out.