It's beginning to seem like Britney Spears has a sip from the Fountain of Youth for breakfast every day, because the "Pretty Girls" singer looks more radiant than ever in yet another steamy Instagram video [2]. In the clip, which she uploaded on Tuesday morning, an incredibly fit Britney shows off some black lingerie, a set of toned abs [3], and two massive tattoos while she dances to an upbeat version of her song "Breathe on Me." Along with the video, she wrote, "Girls just wanna have fun 😉 Never released a video for this song . . . so decided to do a little tease on Instagram instead . . . enjoy!!" Check out her moves above, then see what happened when she met Hillary Clinton [4]!