The media often publishes shocking statistics showing that many of us fail to fulfil even the smallest exercise quotas.
We all know there can be huge benefits to exercising - not only in our physical health, but mental too.
But how much should we be doing to make a difference?
According to top plant-based physician Dr. Michael Greger: "Physical inactivity ranks down at number five in terms of risk factors for death in the United States, and number six in terms of risk factors for disability.
"And, inactivity barely makes the top ten, globally. As we’ve learned, diet is by far our greatest killer, followed by smoking.
"Of course, that doesn’t mean you can just sit on the couch all day. Exercise can help with mental health, cognitive health, sleep quality, cancer prevention, immune function, high blood pressure, and lifespan extension.
"If the U.S. population collectively exercised enough to shave just one percent off the national body mass index, two million cases of diabetes, one-and-a-half million cases of heart disease and stroke, and a hundred thousand cases of cancer might be prevented."
WATCH PBN INTERVIEW DR. GREGER
But how much is enough? Dr. Greger believes health authorities 'have fallen into the same trap as the nutrition authorities, recommending what they think may be achievable, rather than simply informing us what the science says, and letting us make up our own mind'.
Official US guidelines say adults should get at least 150 minutes a week of moderate aerobic exercise (that's just 20 minutes a day).
Dr. Greger says: "It is true that walking 150 minutes a week is better than walking 60 minutes a week.
"Following the current recommendations for 150 minutes appears to reduce your overall mortality rate by seven percent, compared to being sedentary.
"Walking for only 60 minutes a week only drops your mortality rate about three percent. But, walking 300 minutes a week drops overall mortality by 14percent.
"So, walking twice as long - 40 minutes a day, compared to the recommended 20 - yields twice the benefit. And, an hour-long walk each day may reduce mortality by 24 percent."
Dr. Greger is keen to point out that this goes for any exercise - not just walking.
He adds: "This meta-analysis of physical activity dose and longevity found that the equivalent of about an hour a day of brisk, four-miles-per-hour walking was good, but 90 minutes was even better. What about more than 90 minutes?
"Unfortunately, so few people exercise that much every day that there weren’t enough studies to compile a higher category.
"Okay, but if we know 90 minutes of exercise a day is better than 60 minutes, is better than 30 minutes, why is the recommendation only 20 minutes?
"I understand that only about half of Americans even make the recommended 20 minutes a day.
"So, the authorities are just hoping to, you know, nudge people in the right direction. It’s like the dietary guidelines advising us to 'eat less candy'. If only they’d just give it to us straight."