This is quite OT for sports, but not OT for life:
Sign up to be on the bone marrow donor registry. If you fit the criteria, you should have no excuse not to. The foundation covers the cost of lab fees (unless you wish to pay them or donate any amount of money toward it and other donors' fees). However, I read that they will not continue to pay the fees in full after the end of January. I'm betting you can sign up online before then and be clear.
It's easy because you sign up online, they mail you cheek swabs, and you mail them back. If you're worried about actually having to donate, there are actually two procedures, one of which is not the famously painful needle-in-the-bone one. However, if you receive an email or call about a baby with leukemia, or someone's dad, or someone's brother/sister/mother/son/daughter who will otherwise die, you can handle a little bit of pain because it's not as valuable as a life. You have no excuses.