I eat a handful of mixed nuts every morning. I have a bag on my work table. My colleagues started to buy them also, but they usually eat the bag in a day or two. Mine lasts for a couple of weeks.
It is a rule I set upon myself. I eat a handful of nuts each morning and that is it.
I have made many such artificial rules for myself.
I try to go to sleep by 10pm. Wake up even during the weekend by 7am.
I drink a glass of water after each beer or glass of wine.
I use stairs instead of elevator whenever possible.
I keep my mailbox empty and chats read.
And many more.
Once you have such rules internalized as a routine and habit, it helps you with keeping up with them.
You can do this, basically with anything you want to.