The things to focus upon when changing habits are: (Make sure that you include most of these things and you will be more successful than you can imagine).
Pick one thing that you want to differently.
Every morning, visualize how you will look and feel
in three weeks
Write down what you want to do.
Get help to aid you in remembering to do it, for example, a reminder on your phone, a sign on the refrigerator, sneakers by the door.
Ask someone to support you to do this.
Pick a reward for doing it.
And then do it daily for twenty one days.
For more information, you can read:
The Power of habit by Charles Duhigg