Living until the age of 100 may seem like a long life, but, according to a Harvard Medical School professor of genetics, it is possible for humans to live much longer.

According to professor David Sinclair, PhD, co-director of the Paul Glenn Centre for the Biological Mechanisms of Ageing and the author of multiple books on genetics and ageing, growing older is just another disease that humans need to beat.

To accomplish this, however, you don't need pills - you need discomfort.

“The bottom line is you’ve got to get your body out of its comfort zone - hormesis is what we call it,” Sinclair explained on the Rich Roll podcast. “The problem with today’s world is that we just want to be relaxed and fed. We don’t want to feel discomfort, and that’s leading to a whole bunch of problems. If we’re not always telling our body that things could be problematic, our bodies don’t care - they don’t fight against disease; they don’t fight against ageing.”

The methods Sinclair suggests to teach our bodies to combat ageing, and ultimately reverse the process, aren’t new, rather, they have been heard many times before - but they all lead to "discomfort".

Ageing Japan: Robots' role in future of elderly care Show all 15 1 /15 Ageing Japan: Robots' role in future of elderly care Ageing Japan: Robots' role in future of elderly care Residents follow moves made by humanoid robot 'Pepper' during an afternoon exercise routine at Shin-tomi nursing home in Tokyo. Reuters Ageing Japan: Robots' role in future of elderly care Funabashi Hiroshi from A Fun, repairs broken'AIBO's, pet dog robots, at his office in Kasama. Reuters Ageing Japan: Robots' role in future of elderly care A caretaker wearing a 'HAL for care support' robot suit pushes a wheelchair at Shin-tomi nursing home in Tokyo. Reuters Ageing Japan: Robots' role in future of elderly care Residents follow moves made by humanoid robot 'Pepper' during an afternoon exercise routine at Shin-tomi nursing home in Tokyo. Reuters Ageing Japan: Robots' role in future of elderly care Yoichi Suzuki spends time with 'AIBO', a pet dog robot, which his father used for his rehabilitation at his house in Takahag.i Reuters Ageing Japan: Robots' role in future of elderly care A resident approaches humanoid robot 'Pepper' to pat its head during an afternoon exercise routine at Shin-tomi nursing home in Tokyo. Reuters Ageing Japan: Robots' role in future of elderly care A caretaker, wearing walking rehabilitation equipment 'Tree', helps a resident with his walking training at Shin-tomi nursing home in Tokyo. Reuters Ageing Japan: Robots' role in future of elderly care Yoichi Suzuki shows 'AIBO', a pet dog robot, to his bed-ridden mother at his house. Reuters Ageing Japan: Robots' role in future of elderly care A broken'AIBO', a pet dog robot, waits for repair in A Fun's office in Kasama, Ibaraki Prefecture, Japan. Reuters Ageing Japan: Robots' role in future of elderly care A resident touches 'AIBO', a pet dog robot, at Shin-tomi nursing home in Tokyo. Reuters Ageing Japan: Robots' role in future of elderly care A resident touches robot seal 'PARO' at Shin-tomi nursing home in Tokyo. Reuters Ageing Japan: Robots' role in future of elderly care Yoichi Suzuki and his wife take care of his bed-ridden mother as 'AIBO', a pet dog robot walks around at his house in Takahagi. Reuters Ageing Japan: Robots' role in future of elderly care A caretaker wearing a motion assist equipment 'Muscle Suit' carries a resident from a bed to a wheelchair at Shin-tomi nursing home in Tokyo. Reuters Ageing Japan: Robots' role in future of elderly care 'AIBO', a pet dog robot, which Yoichi Suzuki's father used for his rehabilitation, is seen at Suzuki's house in Takahagi. Reuters Ageing Japan: Robots' role in future of elderly care A resident claps to call 'AIBO', a pet dog robot at Shin-tomi nursing home in Tokyo. Reuters

According to Sinclair, the first thing people should do to live longer is to “eat less often”.

“I think the most important thing for increasing healthspan, if there’s just one thing I could say, it would be to eat less often,” he said, adding: “Don’t eat three meals a day.”

The next step, an obvious one for living a healthier lifestyle, is to exercise frequently.

Sinclair also suggests fasting frequently, explaining that he skips “one or two meals a day, and it’s changed my life”.

Fasting is helpful in combating ageing because it boosts Nicotinamide adenine dinucleotide (NAD+) levels, which ultimately makes the body’s “repair genes” more active. The same is true for exposing yourself to hot and cold temperatures, such as in a sauna.

In addition to adequate sleep, the Harvard professor also recommends limiting meat consumption - as the amino acids found in meat activate mTor, a pathway that turns off our body’s defence mechanisms and tells it it is time to grow.

Ultimately, any stressors such as exercise, fasting, and cold/heat stress increase your NAD+ levels, which in turn keep sirtuins, a class of proteins that regulate gene expression and repair DNA damage, functioning properly.

Without NAD+, ageing happens quicker, no matter what your genetic makeup, as Sinclair explained “80 per cent of our health in old age is due to our lifestyle and how we live; only 20 per cent is genetic”.

By taking the effective steps to combat ageing, Sinclair believes that “a world where people could live to 250 and expect to still be playing tennis at 120” is “doable”.