For anyone interested in the relationship between exercise and living longer, one of the most pressing questions is how much we really need to stay healthy. Is 30 minutes a day enough? Can we get by with less? Do we have to exercise all in one session, or can we spread it throughout the day? And when we’re talking about exercise, does it have to be hard to count?

For years, exercise scientists tried to quantify the ideal “dose” of exercise for most people. They finally reached a broad consensus in 2008 with the Physical Activity Guidelines for Americans, which were updated in 2018 after an extensive review of the available science about movement, sitting and health. In both versions, the guidelines advised anyone who was physically able to accumulate 150 minutes of moderate exercise every week, and half as much if it is intense.

But what’s the best way to space out those weekly minutes? And what does “moderate” mean? Here’s what some of the leading researchers in exercise science had to say about step counts, stairwells, weekend warriors, greater longevity and why the healthiest step we can take is the one that gets us off the couch.