A good bee-bopping song tossed into our workout mix every now and then is a great pick-me-up; something catchy that will undoubtedly end up stuck in our heads for the rest of the day, if not the entire week. T-Swift is one young artist who fills this playlist gap quite well - we have to admit, "We Are Never Ever Getting Back Together" is great for holding a 9-minute mile. And since Swift is sitting pretty at the top of the iTunes chart with her grungier hit, "I Knew You Were Trouble" (check out the video), it's time to highlight some of our favorite hits from the star. She may be constantly switching beaus, but it makes for great music. Pop those headphones in and get ready to head bob your way to the gym. Go ahead and sing a little, too - we won't tell.