You don't have to 'just do it' to do what you want, but you need to start doing one thing, that one step to get you started when you aren't listening to others saying that you are not good enough, or crazy.
"I walk into a college campus pool at middle age with competition shorts, goggles, and a cap. I know there are college kids that look and question my sanity, among other questions, but; when I finish, the only place where they remain in my life is in my head if I let it."
I don't hold a chip on my shoulder. It's really not how I try to think. Every now and then I get that pat on the back, or even a tip or two on how to get better. When you go for what you want, the people that scoff will either go off and do their own thing and you won't see them as much, or there will be those that understand because they are trying to win themselves.
-Chris Powers