“Motivation is what gets you started. Habit is what keeps you going.”

According to study published in the European Journal of Social Psychology, adults take an average of 66 days to establish and cement a new habit. (Lally et al., 2009)

https://psychcentral.com/blog/need-to-form-a-new-habit-66-days#At-Least-2-Months-to-Form-a-New-Habit

https://www.ucl.ac.uk/news/2009/aug/how-long-does-it-take-form-habit

What happens in 66 days?

The area in front of your brain called prefrontal cortex is responsible for self control and willpower.  You can improve your willpower to a certain extent and build it like a muscle. While muscles become exhausted by exercise in the short-term, they are strengthened by regular exercise in the long-term. Just like working out or lifting weights builds muscle mass, ‘exercising’ an area of your brain builds neuronal pathways. With increased activity, new pathways are created and that area actually gets physically larger. This process of neuroplasticity or rewiring in the central nervous system (brain and spinal cord) takes place after approximately 66 days, which is the amount of time it takes to develop new habits and patterns.