The second part of the happiness formula is health. It’s never a good idea to take health tips from cartoonists, so check with your doctor if anything here sounds iffy to you. I don’t know how many people have died after reading health tips from cartoonists, but it probably isn’t zero. Don’t say you weren’t warned.

The most important thing to know about staying fit is this: If it takes willpower, you’re doing it wrong. Anything that requires willpower is unsustainable in the long run. And studies show that using willpower in one area diminishes how much willpower you have in reserve for other areas. You need to get willpower out of the system. I’ll show you some tricks for doing that.

My observation is that you can usually replace willpower with knowledge. That isn’t an obvious point, so I’ll give some examples.

Imagine you are hungry and I offer you a delicious but unhealthy dessert. It would take a lot of willpower to resist. Now imagine the same scenario, but I simultaneously offer a healthier food option that is also delicious. Suddenly it is easy to pick the healthy alternative over the dessert. The dessert was only irresistible when the alternative was starving. So the trick for avoiding unhealthy foods is to make sure you always have access to healthy options that you enjoy eating. Your knowledge of this trick, assuming you use it, makes willpower far less necessary.