A new study in mice offers insight into the best time of day to exercise. In a study published in the journal Cell Metabolism, researchers had mice jog on wheels for an hour early in the day and others run the same amount in the evening. Others sat on locked wheels to serve as controls. The researchers then took samples from blood, muscles, and fat. They found that generally, at least in mice, but likely humans as well, morning exercise contributes more to fat loss, whereas late exercise is better for blood sugar control. But if you’re just struggling to go to the gym or hit the road for a run each day, my advice is to pick whatever time you’re most likely to do it at all.