Lewin said that it is not just your personal characteristics, but also your environment that drives your behavior:

Your habits are highly dependent upon context. In many cases, your environment will drive your behavior even more than your personality. So, maybe you’re struggling to stick to that diet because you’re surrounded by bad options or unhealthy people, not because you were born with too little willpower.

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B = f(P,E). Behavior is a function of the Person in their Environment.

Improve yourself and adjust your environment to make good habits easier and bad habits harder. If you can do those two things, sticking with better habits will be much easier.

With personality, the key is to believe you can improve:

Carol Dweck, a Stanford professor, has become well-known for her work analyzing the differences between the fixed mindset and the growth mindset. When you are using a fixed mindset, you believe that your abilities in a particular area are fixed. When you are using a growth mindset, you believe that you can improve, learn, and build upon your current abilities.

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Your identity and beliefs play a role in your habits and if you’re looking to create a new identity, you have to cast a vote for that identity. The best way to improve your abilities and skills is through deliberate practice.

With environment, you can do what BJ Fogg calls “designing for laziness” :

Fogg wanted to reduce the amount of popcorn he ate, so he took the bag of popcorn out of his kitchen, climbed the ladder in his garage, and put the popcorn on the highest shelf. If he really wanted popcorn, he could always go to the garage, get the ladder, and climb up to get it. But his default decision when he was feeling lazy would be to make a better choice. By designing his environment for laziness, Fogg made it easier to stick with healthier habits. I have mentioned a variety of other ways you can design for laziness in this article.