Exercise those options when you can

A lunchtime walk -- even if it's short -- counts toward your daily 30-minute exercise requirement.

How little exercise can you do and still be healthy?

The American College of Sports Medicine (acsm.org) -- along with the American Heart Association (americanheart.org) -- recently updated its physical-activity guidelines for the first time in 12 years. They recommend:

• Moderately intense cardio (like power walking) 30 minutes a day, five days a week, or vigorously intense cardio (like running) 20 minutes a day, three times a week. It's OK to get the 30 minutes of cardio in 10-minute bouts -- try a walk before breakfast, one at lunch and another after work.

• Eight to 10 different strength-training exercises (like push-ups or stomach crunches), eight to 12 times each, twice a week. If you're over 65, add flexibility exercises (like stretching) at least twice a week, and consider balance exercises to reduce the risk of injury from falls.

The bottom line: get moving. Even some activity is better than none.

"Walk during TV commercials if nothing else," says Steven Blair, a co-author of the report. Finally, set a schedule, write it down -- and do it.