Decide once
Make rules instead of decisions.
I think this was something I heard Seth Godin say—if you want to start a new habit, it’s better to have a rule for enforcing your new behavior rather than making decisions in the moment.
For example, let’s say you want to get in shape, so you decide to work out three times a week. If that’s your only guideline, it means you have to decide every day whether you should go to the gym or not. And every time you’re forced to decide, you risk making a decision you’ll regret later. Maybe you didn’t feel like going to the gym three days in a row, and all of a sudden it’s Thursday.
Contrast this with deciding to go to the gym on Mondays, Wednesdays and Fridays. If you wake up and it’s Monday, you don’t need to make a decision—you know it’s a gym day. Decide on a rule and you only have to decide once.