Daniel E. Lieberman

I mean, for every system of the body, physical activity has benefits that slow the aging process. And so when you stop doing it, and that's the way in which you perceive it as accelerating aging. But really, it's the absence of physical activity which lets aging run amok.

I mean, for every system of the body, physical activity has benefits that slow the aging process. And so when you stop doing it, and that's the way in which you perceive it as accelerating aging. But really, it's the absence of physical activity which lets aging run amok.

Yeah. Yeah.

Yeah. Yeah.

Well, I mean, I think part of that is depression, right? When you lose a partner, I mean, grief and depression, your cortisol levels go up, your immune system goes down. I mean, it's really tough on your body. I mean, psychosocial stress plays a serious physiological toll. But also, as you just pointed out, when people retire, they become less active.

Well, I mean, I think part of that is depression, right? When you lose a partner, I mean, grief and depression, your cortisol levels go up, your immune system goes down. I mean, it's really tough on your body. I mean, psychosocial stress plays a serious physiological toll. But also, as you just pointed out, when people retire, they become less active.

And that loss of activity has enormous effects on every aspect of our body and our minds. I mean, physical activity is important not just for physical health, but also vital for mental health and health. And I think a lot of the problems that mental health issues we have today, depression, anxiety, some of them, to some extent, we can attribute that to less physical activity.

And that loss of activity has enormous effects on every aspect of our body and our minds. I mean, physical activity is important not just for physical health, but also vital for mental health and health. And I think a lot of the problems that mental health issues we have today, depression, anxiety, some of them, to some extent, we can attribute that to less physical activity.

And as people age, becoming less physically active, again, makes them much more vulnerable to a wide suite of diseases.

And as people age, becoming less physically active, again, makes them much more vulnerable to a wide suite of diseases.

Or if you do retire, I mean, retiring is, again, another modern weird thing, right? Nobody retired in the past. I mean, if you're a farmer, it's like a subsistence farmer and name it any place, right? It's not like suddenly you hit 65 and all of a sudden you no longer have to work in the fields. You work in the fields until you're dead, right? And hunter-gatherers don't retire.

Or if you do retire, I mean, retiring is, again, another modern weird thing, right? Nobody retired in the past. I mean, if you're a farmer, it's like a subsistence farmer and name it any place, right? It's not like suddenly you hit 65 and all of a sudden you no longer have to work in the fields. You work in the fields until you're dead, right? And hunter-gatherers don't retire.

They continue to be physically active until they die, right? Or until they get too sick. So it's a very modern Western concept. And yes, we do pay a price for it. But you, of course, can replace... work that you do with challenging, rewarding, fun things to do. The important thing is just not to stop being physically active.

They continue to be physically active until they die, right? Or until they get too sick. So it's a very modern Western concept. And yes, we do pay a price for it. But you, of course, can replace... work that you do with challenging, rewarding, fun things to do. The important thing is just not to stop being physically active.

One of my favorite studies ever published, without a doubt, is a study done by a guy named Ralph Paffenbarger. He realized that places like Harvard are fantastic for studying aging because Harvard, like other private universities, never lets go of their alumni. So until the day you die, they're asking you for money on a regular basis.

One of my favorite studies ever published, without a doubt, is a study done by a guy named Ralph Paffenbarger. He realized that places like Harvard are fantastic for studying aging because Harvard, like other private universities, never lets go of their alumni. So until the day you die, they're asking you for money on a regular basis.

And so he got the Alumni Association, the Harvard Development Office, to let him follow a series of Harvard alumni from several years and keep asking them and questions about their physical activity levels and also their diet and whether they smoked and stuff like that. And then you track them for 25, 30 years.

And so he got the Alumni Association, the Harvard Development Office, to let him follow a series of Harvard alumni from several years and keep asking them and questions about their physical activity levels and also their diet and whether they smoked and stuff like that. And then you track them for 25, 30 years.

And what he found was that the alumni, we have to correct it for every factor you could think of, that as the alumni got older, the effect of physical activity on their health outcomes was bigger and bigger. So alumni who were in their 20s, 30s, and 40s, for example, who were exercising four or five times a week, they had about 20% lower death rates.

And what he found was that the alumni, we have to correct it for every factor you could think of, that as the alumni got older, the effect of physical activity on their health outcomes was bigger and bigger. So alumni who were in their 20s, 30s, and 40s, for example, who were exercising four or five times a week, they had about 20% lower death rates.