Britney Spears is having some fun dancing around. In a video shared to Instagram on Thursday, the 39-year-old pop singer is seen showing off her moves to "Pumped up Kicks." She wore a white sports bra and black shorts paired with brand new tennis shoes. Spears included a lengthy caption where she touched on a number of things including her new tennis shoes, receiving advice and keeping dreams alive. "So what do you guys do to keep your dreams alive ????" Spears began her post.