FOR FITNESS, PUSH YOURSELF. “Intense exercise changes the body and muscles at a molecular level in ways that milder physical activity doesn’t match, according to an enlightening new study. Though the study was conducted in mice, the findings add to growing scientific evidence that to realize the greatest benefits from workouts, we probably need to push ourselves. . . . Catecholamines are released only during exercise that the body perceives as stressful, he said, so without some physical strain, there are no catecholamines, no messages from them to the CRTC2 protein, and no signals from CRTC2 to the muscles. You will still see muscular adaptations, he added, if your exercise is light and induces no catecholamine release, but those changes may not be as pronounced or complete as they otherwise could have been.”

This has been my experience. For years I went to the gym regularly, but I was really just going through the motions. Working harder lately, I’m seeing bigger gains.