Remove all necessary hassles and steps to an action. The more hassles and steps there are, the more mental and physical energy it takes to complete an action. Making an action as mentally easy as possible makes it more likely to be completed.
Conversely, if you want to discourage a behavior, add hassles and additional steps to make it harder to do.
Make it as easy as possible for someone to do an action - simplify the steps as much as possible.
Encouraging a behavior: Consider removing fields on forms or having some sections pre-filled.
Discouraging a behavior: If a person wants to withdraw from their savings, make them write a 1-page essay on why their present self needs the money more than their future self.
