Human beings are not sloths. "We need to move," Harvard psychiatrist John Ratey has explained. "It's only 10,000 years ago that we were hunter-gatherers and we moved anywhere from 10 to 14 miles a day."

Which might sound kind of alarming to you.

While we all know that too much sitting around is horrible for both our mental and physical health, do you need to walk the equivalent of a half marathon every day to avoid the nasty health consequences of a sedentary lifestyle? If so, many would understandably throw up their hands in defeat and plotz back down on the couch for another episode of their favorite show.

Luckily, a growing body of science shows that while our ancestors may have all been dedicated athletes by necessity, we can achieve major gains in health with rather minor changes to our lifestyles.

Daily half marathons not required.

The blog for The Blue Zones, a recent book on well-being research, just highlighted one particularly convincing study on the lifestyles of no less than 140,000 people. The essential finding was that lowering your chance of a premature death was surprisingly achievable.

"The study from the American Cancer Society followed 140,000 older adults and reported that those who walked six hours per week had a lower risk of dying from cardiovascular disease, respiratory disease, and cancer than those who were not active, but that walking even as little as two hours per week could begin to reduce the risk of disease and help you live a longer, healthier life," writes Aislinn Leonard on the site.

Six hours a week is doable. Two hours a week -- or just slightly more than 15 minutes a day -- should be downright simple. And while this massive study looks pretty conclusive, it's hardly the only research suggesting you need less exercise than you think to significantly impact your health. Recent findings out of Canada show that just ten minutes of light exercise can positively impact your cognitive performance, for instance. 

You don't even have to join a gym.

You don't even have to join a gym or take up a sport. "The world's longest-lived people don't pump iron, run marathons, or join gyms. Instead, they live in environments that constantly nudge them into moving without thinking about it. They grow gardens and don't have mechanical conveniences for house and yard work. They have jobs that require them to move or get up frequently. And they walk every single day," notes Leonard.

You're unlikely to give up your washing machine and scrub clothes by hand to live as long as the slim and healthy Amish, but experts suggest even just getting a dog and taking it for regular walks might be enough to move the dial on your health and add years to your life. Or if you're not an animal lover, setting a reminder to get up for a five-minute walk around the office every hour or opting for walking meetings can make a difference.

Bottom line: while a super active lifestyle is great if you can achieve it, don't think small changes to your routine won't have big impacts. A couple of tweaks to your daily routine could add years to your life.