How do I convince my parents to let me cheer?

My mom absoloutly HATES cheerleaders, and I have been to practices with my friends and I love it! She said Hell would freeze over before I became a cheerleader, I offered to pay and find my own transportation but she still said no. I said it would be good exercise and she told me I didn’t need anymore exercise( Which I do) my dad disagrees but my mom “Rules” the house. I asked my dad to convince her and he said he didn’t want to get her mad. What do I do?