Experts say that sitting is one of the biggest factors contributing to obesity and heart disease, so people need to get up and get moving.

It can lower your risk of high blood pressure, high cholesterol and diabetes as much as running can, according to a 2013 study that compared approximately 33,000 runners and 15,000 walkers over six years.

The American Heart Association designated National Walking Day on Wednesday to encourage physical activity. According to the AHA, 150 minutes of moderate physical activity per week, which is easy to remember as 30 minutes of walking a day,  five days a week, can help prevent weight gain and lower the risk of obesity, as well as improve mental well-being and increase energy and stamina. It may also reduce the risk of osteoporosis, breast cancer and colon cancer.

National Walking Day is a time to clean the slate and remove self-blame, said Dr. James Levine, professor of endocrinology at the Mayo Clinic in Phoenix, Arizona, and the co-director of Obesity Solutions, a collaboration between Mayo Clinic and Arizona State University.  Levine led a team that invented the treadmill desk.

He said there’s no excuse for not becoming more active.

“Let’s take the word ‘excuse’ off the table and put ‘opportunity’ on the table,” he said.

He said if people can walk across the living room, they can resolve to do it three times a day. If they use a wheelchair and are physically able, they can propel themselves an extra five minutes a day. People who are out of condition can start with a 10 minute walk three times a week at a local mall.

Inactivity, particularly sitting, is one of the biggest factors contributing to obesity and heart disease, Levine believes.

Hours of stressful sitting at her sales job may have contributed to Bev Pohlit’s heart attack at age 55.

Less than a year after that heart attack, she now starts every day at 4:20 a.m. on the treadmill. She walks at lunch and again after dinner to fit in 10,000 steps. Her FitBit, plus a push from other women posting their daily steps on Facebook upped her commitment to walking.

“If I missed a day of walking it used to be no big deal,” she said.  Now, she gets upset if she doesn’t get in her goal.

A recent American Journal of Preventive Medicine analysis of other published studies covering 54 countries reported that sitting more than three hours a day was responsible for about 4 percent of deaths from all causes, about 433,000 deaths.

A 2010 study said that sitting more than six hours a day led to higher death rates than sitting less than three hours: 40 percent higher for women and 20 percent higher for men.

Some say that taking frequent walks may be the antidote.

Last fall, U.S. Surgeon General Dr. Vivek Murthy said one of the most powerful things to “turn the tide on chronic disease is walking,” in a call to action saying walking more can help prevent heart disease, obesity, cancer and diabetes.

Although there’s no doubt that working out at the gym a few hours a week is good for you, Levine said it still doesn’t offset long periods of sitting.

“Sitting all day long is bad for your body and bad for your mind.”

He said daily inactivity has evolved over 200 years as society moved from being agriculture-based to office-based. He refers to the office chair with wheels as the “master of destruction,” with computers setting the “chair sentence.” He said approximately half of all jobs are now linked to chair-based, desk-based computer work.

“All the active parts have vanished from our way of looking at the world,” he said, encouraging people to move.