You want to exercise more. But rain, fatigue, looming deadlines, and bad sneakers (that’s right—blame the sneakers) get in your way. What is really going on? Why do dieters falter and armchair athletes remain seated? Turns out it’s not about “weakness.” (We can all stop beating up on ourselves right now!) And what we’re learning about the brain points to new strategies that will really—finally!—make all the difference.