An interesting study about precommitment and how using precommitments reduces the amount of willpower you need to make decisions that will reward you in the long term.
Researchers took a look at 83 scientific studies of willpower depletion to try and determine what the five most popular causes are. Their conclusion:- effort, perceived difficult, negative affect, subjective fatigue and blood glucose levels.
One of the most comprehensive studies that we have regarding the habit formation model. The study consisted of 96 volunteers and showed that the average time required for forming a habit was 66 days but the range was between 18 and 254 days.