“Why can’t I just do the things I know I want to do?”

Tell me if this sounds familiar: You resolve to make a change for the better in your life. Maybe to walk more. Or to stop drinking. Or to pick up that breathwork habit again. You tell your partner about it. You put your resolution in writing. You actually make the change. It works. It feels good! You’re happy about it. Your partner is thrilled. Then you backslide. Why? Are you some kind of slob who has no willpower? Biology tells us: not necessarily. Backsliding is a universal experience. Every one of us resists significant change, no matter whether it’s for the worse or for the better. Our body, brain, and behavior have a built-in tendency to stay the same within rather narrow limits, and to snap back when changed—and it’s a very good thing they do! Ultimately, your nervous system doesn’t care about your good intentions. It cares about keeping you alive. Just think about it: if your body temperature moved up or down by 10 percent, you’d be in big trouble. The same thing applies to your blood-sugar level and to any number of other functions of your body. So your system is constantly keeping track of what’s changing and adjusting as necessary. This condition of equilibrium, this resistance...