How to gain goodwill and experience for use in a future race

I am currently a dentist in my small(ish) town in Idaho. I am in my mid-late 30s, and my career/family takes up most of my time right now. At the same time, I can foresee a future 10-15 years from now when I would really like to run for local office, with the ultimate goal being that of a state congressman as I near retirement age. Question: What things should I be doing now? What are some good and meaningful ways of getting involved that don't require the equivelant of a second part-time job?