I want to open up a business to help people lose weight but don't know how. ?

Most weight loss places don't care about their clients only getting a check. I'm a successful marathon runner and triathlete and live working out. Shows like the biggest loser break my heart. It tears me up seeing obese people work so hard and see them make their goals. I wanna do tge same. I want to help people reach their goals, weather it's losing 100 pounds, running an ultra marathon or whatever. I want to talk to clients as much as possible and really help them with nutrition and workouts but I'm just not sure how to get started. Any tips?