It can look almost too easy: athletes gliding along on a bike, runners shuffling at a pace slower than most people's warm-up, or someone strolling so gently it barely seems like exercise at all. Yet ...

It can look almost too easy: athletes gliding along on a bike, runners shuffling at a pace slower than most people’s warm-up, or someone strolling so gently it barely seems like exercise at all. Yet ...

The “zone zero” fitness trend promotes very low-intensity movement, like walking and housework. Here’s what it can — and can’t — do for you. By Danielle Friedman When you’re exhausted, burned out or ...