'Toxic' singer Britney Spears tweeted a video of herself doing yoga ? sans mat ? in multiple rooms in her hotel room, telling her fans that's one of the ways that she keeps her sleek physique in tip top shape. She shares, "Traveling from hotel to hotel can make you a little stir crazy, so I decided to start doing 2 hours of yoga in each room! I was very sore the next day, but at least I got to use my time wisely."