Watch as Kevin Hart Hilariously Overcomes the Odds to Work Out With Serena Williams

Working out is better with friends — especially if those friends are Serena Williams and Kevin Hart. The two celebrities recently paired up for a workout on the Nike+ Training Club app, and the promo videos are hilarious to watch. While the workout itself is nothing short of intense — a 15-minute high-intensity bodyweight circuit, which includes push-ups, high knees, and jump squats — the real treat is watching Serena and Kevin together. Always the consummate pro, Serena looks unfazed as Kevin gives all sorts of excuses as to why he can't get into certain moves. "I retain a lot of water weight in my hamstrings," explains Kevin. "When I drink water, I digest it, but it goes to my hammies, and that's why I can't touch my toes. . . . Trust me, I want to, but I have water hamstring-itis!" Not to be held back by this fake debilitating disease, Kevin makes a point to school Serena during the workout — at least in his own head. If you're in need of a laugh, check out the videos of the pair together, then try the workout for yourself!