Work on your self-control.

Protect your willpower.
Remove temptations from your environment and avoid situations and places where you may be tempted. For example, if your goal is to lose weight, get the bad food out of the house, and stay away from shelves with unhealthy food when shopping.

Improve your cognitive executive functions.
Find some good exercises or games to improve memory operation, cognitive flexibility, adaptability, and impulse control.

Delay gratification.
Practice gratification delay. Every time you experience an urge for some pleasure, delay it as much as possible.