I've just started trying to come up with a list of the bare minimum of things we should do every day to be happy and healthy.

This list doesn't include major challenges, like "Quit smoking." Obviously, quitting smoking is very important for health, but it's not easy to add to a to-do list. This list doesn't include items like "Spend less time on the internet" or "Read more" because they aren't universal enough. This list also doesn't include items related to attitude: gratitude, cheerfulness, and the like. These are very concrete, very essential things to do as part of the everyday routine.

Here's what I've come up with so far...
Wear your seat belt
Take prescriptions medications properly
Go for a ten-minute walk (preferably outside)
Put your keys and wallet away in the same place
Take something with you (for instance, drop your dirty socks in the hamper on your way from your bedroom to the kitchen)
Charge your phone
Connect with someone close to you
Go to bed in time to get a good night’s sleep