Gradual is the app that I've always wanted. I believe that our society does not put enough emphasis on monitoring and acting on our health data until there's already a major problem. I built gradual to unify of my health metrics (ie physical activity, sleep, HRV, vO2 max etc) and map it against peer reviewed research and population norms to flag the areas that require the most attention. Most importantly, all of your health data remains on your own private iCloud. Users aren't even required to create an account.