For me this was the biggest insight that dramatically improved my ability to form habits. I don't actually decide things most of the time. Agency is something that only occurs intermittently. Therefore I use my agency on changing what sorts of things I am surrounded by rather than on the tasks themselves. This works because the default state is to simply be the average of what I am surrounded by.

Cliche example: not having junk food in the house improves my diet by making it take additional work to go out and get it.