Nearly two-thirds of American adults are considered overweight by the Centers for Disease Control and Prevention. But losing weight, being more active and getting fit in the few waking hours not spent at work can seem like a lost cause.

Health guidelines suggest that people get 30 to 90 minutes of exercise a day, three times a week. The eight hours -- or more -- spent at the office can offer some additional opportunities, without cutting into family time or other obligations.

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While you probably don't have dumbbells stashed under the desk, using your own body weight, stretching and moving around when you get the chance will help you be more active and energetic without going far from your desk.

Jon A. Kaplan, fitness and wellness director at Meadow Mill Athletic Club in Baltimore, said the workplace is a perfect opportunity to increase your activity in the day. He said there are simple stretches and movements to help you reach your daily exercise goals and care for your body.

Kaplan suggested people become aware of repetitive activities that can cause pain and damage and find ways to counterbalance them. If you cross your legs one way throughout the day, he said, switch it up and cross them the other way so you aren't putting constant strain on one side of your body.

Another thing to notice when sitting is the angle of your chair. A recent article in the New York Times quoted a study claiming that sitting up straight in your chair is actually bad for you. Researchers at the University of Aberdeen in Scotland found that moving your sitting position to 135 degrees -- tilted slightly backward -- is preferable.

The researchers observed 22 volunteers who sat in three positions. The article said the first two positions, sitting upright and sitting with the body hunched forward, produced the greatest spinal disk movement, causing the internal disk material to misalign.

The third position -- a 135-degree angle with the feet on the floor -- created the least strain. According to the study, leaning back places less pressure on the spine.

While you're stuck in a chair, there are still things you can do that focus on your core muscles. Kaplan said that tightening and relaxing your stomach muscles helps work your abs and your lower back. You can also do neck stretches, shoulder rolls and scapular squeezes without moving away.

Get Out Of The Chair

Kaplan wants people to go one better than changing their seat backs. He wants them to get out of the chair.

"Get up and stretch whenever you can," he said. "Do lunges with good form. Do heel taps (bouncing on the toes). The vibration also helps with bone density."

He also suggested side stretches to help with the back and hamstring stretches to involve the legs, which are usually dormant during the workday. Kaplan said people should take the stairs rather than an elevator to get their body moving.

Instead of using the phone or instant messages to talk to a co-worker, get up and go visit face-to-face. Do anything, Kaplan said, to get up and get moving.

"Break the repetitious activities," he said.

Carrying All That Weight

Kaplan said there are also some activities that seem innocuous but could affect your posture and your core muscles. Most people carry a briefcase, purse or backpack; he suggested switching shoulders from time to time to keep your body from listing from one side to the other.

As part of a total wellness plan at work, Kaplan said not to eat at your desk. By getting up to nosh elsewhere, you get some physical activity and a change of scenery to help your mental activity as well.

"It is a mental thing," Kaplan said. "It is as part of a weight-control issue. We need to have balance in our lives." Other Links:

Save Money On Fitness

Stretching Guide

Ergnomics Help You Stay Healthy

Ergonomics To The Rescue

Fitness.gov

Be Active Each Day