If you don't get enough exercise for the amount you eat, you may put on weight. This can lead to obesity. To keep your health and weight in check, you should have at least 30 minutes of physical activity on most days of the week. But fewer than one-third of Americans do this.¹

• Our modern lifestyle makes it harder to burn calories. We tend to go everywhere in cars, and watch sports on television rather than playing sports. And we spend more time sitting at computer screens.
• It might seem as though we're rushing around doing a great deal. But it's no longer common for people to carry heavy groceries, cycle or walk to work, do heavy chores around the house, or dig in the garden.
• We have to make a special effort to take any exercise at all. It can be difficult to find time for exercise. Many Americans work long hours and spend little time on vacation.

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment. ©BMJ Publishing Group Limited 2008. All rights reserved.