"Lots of calorie counting apps, activity trackers, motivational reminder apps, etc."

but how is this an untapped opportunity when there are already tons of products and companies trying to solve it? short of building an app that evaporates body fat?

some of these apps do work. i know a lot of people who had success counting calories with MyFitnessPal. but you cant force everybody to count calories. you cant force people to count their steps. so i just dont understand what opportunity you see here.