How do I tell my Dad?

How do I tell him I don't want to swim? I have been swimming for a few years now and I'm really good[sorry, don't mean to sound like an ego-brat]. I've been in the newspaper because of my swimming, and I really enjoyed it. But, I'm starting to dislike it more and more. I know it won't lead anywhere into my future, It's not what I want to do. I'm only in 8th grade, but I want to do dance. I did it when I was 5, like most little girls. But, whenenver I do dance, I get these tingles up my spine like it's where I belong. I dance in my room alot and watch Dancing with the Stars. Sorry this is sounding like a sob story... Anyway, my dad is really competititve and always says stuff like "Youjust gotta try harder" and "I'm really proud of you" so that always makes it more hard to tell him. Don't get me wrong, I love swimming but I want to change to something I REALLY love. I have 3 older half-brothers that were all VERY athletic, so it's hard to live up to that. Before I was born, our family was named the most athletic in Reno, Nevada, though they don't live there anymore. I've been looking up dance stuff on the internet, and I'm getting more and more intrested. So, my big Q? is, how do I tell my Dad? I know I can tell my mom, but my dad is a little tough...Please and Thank you! :]