I'm 49 and attempting to start a new career owning a running store. Well I'm attempting to attempt it...I've yet to do any positive action yet other than to be an athlete, but with luck fairly soon I'll be getting some experience in the field.

So one possibility is a triathlon-related store. As the owner of such a thing, you're in a perfect position to help with local runs/rides/races and get involved with clubs. Maybe get a side job as a track coach at a school. (These are all things I consider I could do as well.)

Start networking. This is my personal failure. (That and a complete lack of cash onhand.) Don't let it be yours.

Keep dreaming and asking around, talk to people, and keep all your options open. It's good to dream and plan. You never know.