Best book I've read for understanding/improving willpower

I'm currently reading Willpower Instinct by Kelly McGonigal and every chapter I'm more impressed with how applicable it is to my life & health goals. It's explaining a lot of the behaviors I've seen in myself and concrete ways to combat them. This isn't a "just try harder" approach. That doesn't work! Healthy eating/lifestyle has been something I've been working on for decades.

The most recent chapter focused on how we give ourselves license to indulge after we've been "good" (or tell ourselves we will be good in the future). Like, 'I am having a salad so this cheeseburger is ok'. Or, 'I can have this steak now because I'll go work out tomorrow'. That's only one tiny example of content but I'm thoroughly enjoying the book and wanted to share.