An active lunchtime can range from the sweaty to the serene, experts say, from a full-out cardio blast to a walk in the park.
"Think about it. Thirty minutes on a regular basis would meet the minimum threshold for physical activity," he added.
U.S. government guidelines state that adults 18 and older need 30 minutes of physical activity on five or more days a week to be healthy.
For an intense workout on a rainy day, Bryant suggests finding a quiet stairwell and performing a series of lunges, dips, push-ups, alternating quick and slow climbs, or taking the stairs two at a time.
"You can do a mix of cardio, interval and resistance training using the stairs," he explained.
How intense should your midday workout be? For many, perspiration is the dividing line.
"Sweating is a huge obstacle for most people," said Bryant, "but just sitting at the computer compromises posture and has health consequences."
As author of "Walking Deck: 50 Ways to Walk Yourself Healthy," Florida-based fitness expert Shirley Archer has helped workers to organize lunchtime walking groups.
"If you haven't had a chance to pace out the walks in advance, simply walk 12-15 minutes and then turn around and re-trace your steps," Archer said. "You will be back in time."
Elasticized exercise bands or tubing can add toning moves to a walk, she said, adding that intervals, circuits and hills would also add variety.
"Keep a water bottle and pair of walking shoes in your desk at all times," she recommends. "Do not take these home."
If cardio needs are met outside the office, lunchtime might be better spent in strength and toning exercises, she said.
Archer also suggested trying to cultivate mindfulness and deep breathing.
"More meditative-style movements can be a refreshing mid-day break from office stress," Archer said.
For people with a gym membership, the 30-minute treadmill run is a popular option, according to California-based trainer Amy Dixon, who added that many gyms tailor short fitness classes to the lunch crowd.
"You have to prepare for a quick and dirty workout in the middle of the day." said Dixon, creator of the "Give Me 10" and "Breathless Body" fitness DVDs.
"For women, you want waterproof mascara, cool towels, a change of clothes, and something to keep your hair off of your face."