Earlier quoted context omitted.
Seemingly small things like flossing and using your non-dominant hand to open doors improve self control. Deceptively small things like that lead into bigger things.
Whoa can you explain what you mean by using your non-dominant hand to improve self-control?
Fighting off this urge and continuing to use the non-dominand hand at something you are bad at improves self-control. You put yourself in a position where you don't quit when something works poorly for you. You make a habit of sticking with things to get better. It's worth cultivating habits that get you exploring things you're bad at.
I admit shaving with the non-dominand hand gets dangerous. But you can witness this effect by trying something simpler like stirring a glass of milk or brushing your teeth.