One of the most modifiable of risk factors for obesity is physical inactivity (Grundy et al 1999). In unveiling new health objectives, the US government dramatically increased target exercise goals. To maintain a healthy weight, the NIH now recommends that adults engage in 30 to 60 minutes of exercise most days of the week. For weight loss, or for people who have recently lost weight and want to keep it off, the recommendation is between 60 and 90 minutes of exercise most days of the week (MMWR 2002). Consult your physician before embarking on any exercise program.