Daily	2–3x/week	4–5x/week	Never
Low-level exercise (at least 30 min of light physical effort and no noticeable change in breathing, e.g., walking)
Moderate exercise (at least 20 min of moderate physical effort, making you breathe somewhat harder than normal, e.g., carrying light loads, bicycling at a regular pace, or doubles tennis)
Vigorous (at least 20 min of hard physical effort and marked rise in heart rate and breathing, e.g., heavy lifting, digging, aerobics, or fast bicycling)