There are frequent references on this forum about the marshmallow test...and posts about people who keep making bad decisions, especially with regard to saving & spending...and it's often thought to be due to a lack of self-control.
Here's an interesting article about self-control/willpower.
"The students who exerted more self-control were not more successful in accomplishing their goals. It was the students who experienced fewer temptations overall who were more successful when the researchers checked back in at the end of the semester. What’s more, the people who exercised more effortful self-control also reported feeling more depleted. So not only were they not meeting their goals, they were also exhausted from trying."https://www.vox.com/science-and-heal...rol-psychology