I think that is is better to make slow changes and small manageable commitments.
If you set the bar too high you are more prone to failure and once you do you will feel guilt and that since you already failed what does it matter.
If you make very small commitments ie. I will not smoke and only vape in the first hour each morning. If you smoke after that it isn't a failure.
You can gradually increase the time without a high risk of failure and guilt.
This is based on research on forming new habits.
Yes I had a moment on Monday evening where I felt that I'd let everyone down and was feeling really down thinking what have I done, this year has just been so tough with trauma and bereavement in the family that I just needed an outlet