Only half of Americans got enough exercise last year - here's how much you should be doing

For all you couch potatoes out there, here's some inspiring news: More American adults than ever are getting enough exercise during their free time, according to a new report released by the CDC.

Between January and September 2015, roughly half of adults met the government's 2008 guidelines for physical activity by exercising in their leisure time. That's up from just 41% in 2006.

But we still have a long way to go.

To meet government guidelines, you should be doing at least 2.5 hours a week of moderately intense aerobic exercise, or 1 hour 15 minutes a week of vigorous aerobic exercise, or a combination of the two. You should also be exercising at least 10 minutes at a time, ideally spread throughout the week.

Exercise trends among Americans

This chart shows the percentage of adults aged 18 and over who met 2008 federal physical activity guidelines in their free time. As you can see, the fraction of Americans who met the exercise guidelines rose and then fell during the late 1990s and early 2000s, but there's been a steady uptick since about 2007:

Not surprisingly, we get less and less (leisure-time) exercise as we age. While about 60% of 18- to 24-year-olds met the government's requirement, only about half as many people over 75 did, as the chart below shows:

Men were also slightly more likely than women to get enough exercise during their free time. In total, about 53% of men met the requirement, whereas 47% of women did.

The results also varied by ethnicity. After taking into account people's age and sex, about 53% of white adults met the 2008 exercise guidelines, whereas only 44% of Hispanic adults, and 44% of black adults did.

How physical activity was measured

The new findings are based on data from the National Health Interview Survey, which collects data on a range of different health topics from household interviews.

According to the CDC, the number of Americans who are getting enough exercise may have been underestimated, because the report only looked at leisure-time exercise, whereas the 2008 guidelines refer to any type of exercise.

Other health trends

In addition to fitness, the report also includes estimates of obesity, tobacco and alcohol consumption, and other health measures.

The numbers of obese adults aged 20 and over expanded from 19% in 1997 to 31% in January to September 2015. On the other hand, smoking has declined over the same period, from 25% in 1997 to 15% in January to September 2015.