An obese person can be happy as long as they don't peg their happiness on being able to do a bunch of physical activities. Plus, all the time spent not working out can be spent on pursuing other interests.
A dumb person can be happy. There are billions of us.
A short lived person can be happy- it's more about the quality of life than the quantity.
So if I can live in a world in which I don't have to do a bunch of physical activity, can play with the screens that I want, and can enjoy my life? I don't actually need a lot of the things that a doctor says I need. To be fair, an obese person has a higher chance of being hospitalized, which sucks, so being dumb and obese will probably lead to me being less happy.