If you’ve read, heard or watched the news in recent years, you know that health officials and researchers have long warned that Americans are unfit. Rather than wait for the follow-up study that finds a lack of exercise is the reason for our collective unfitness, go for a walk, go skiing, anything to be active. Encourage the kids to use the gift certificate from Aunt Martha or the money from Grandma to buy a sled or a pair of ice skates.

In a study in the current Journal of the American Medial Association, researchers at Northwestern University found a large portion of Americans are not physically fit. Reasons for this include the decline of physical education classes in schools, neighborhoods that are not designed for walking and the growing popularity of video games.

The researchers asked kids and adults to walk or run on a treadmill, then measured their heart rate and blood pressure. More than one-third of the adolescents fell into the bottom fitness level. The unfit kids were more than twice as likely to be overweight, according to the study. They were two to three times as likely to have high cholesterol than were kids with higher fitness scores.

Of the adults, nearly 14 percent who did the test were physically unfit. Based on their findings, researchers estimate 7.5 million adolescents and at least 8.5 million adults are out of shape. Because people over 50 and people with serious health problems were excluded from the treadmill test for safety reasons, the real number of out-of-shape adults is likely much higher.

“This really points out that the low level of physical activity in our population is leading to a lot of kids and adults having low fitness levels, and those low fitness levels are related to a lot of bad outcomes,” James O. Hill of the University of Colorado Health Sciences Center told The Washington Post. “We haven’t been able to communicate to the public what a crisis this is. It’s scary. Maybe this will be a wake-up call.”

So wake up and get active. That’s a New Year’s resolution worth keeping.