Read the full transcript of exercise scientist Keith Diaz’s talk at TED2026 on April 15, 2026.
Editor’s Ntoe: In this insightful talk, exercise scientist Keith Diaz explores how our increasingly sedentary modern lifestyles are taking a hidden toll on both our physical and mental health. He shares evidence-based research demonstrating that small, frequent “movement breaks” throughout the day can significantly combat these effects, leaving us feeling more energized and focused.
From Summer Camp to the Office: A Personal Shift
KEITH DIAZ: My favorite job ever was as a summer camp counselor, where it was basically paid to play games with kids all day. We played capture the flag, running bases, dodgeball, went swimming in the pool every day. And at the end of the day, I’d be tired, but in a good way, not mentally drained, but physically tired, a satisfied kind of tired, where I’d use my body to complete a hard day’s work.
Flash forward, and my job today looks very different. (Laughter) Even though I’m an exercise scientist, I don’t get to actually do any exercise at work. Instead, my days consist of staring at a computer screen and sitting in countless meetings.
The transition for me to office work was jarring. I no longer had those same feelings of satisfaction at the end of the day’s work. I was so tired, exhausted, actually, but I hadn’t used my body at all. And this shift that I experienced, I’m not alone in feeling.
The Most Sedentary Era in Modern History
We are living in the most sedentary era in modern history. In a single year, the average adult now spends a full 187 days, over half of the year, sitting or physically idle. The bad news is that our bodies weren’t designed for this.
I know because I’ve spent my career as a scientist studying the harms of being highly sedentary. And what scientists have found is that being highly sedentary increases your risk of diabetes, cancer, dementia, heart disease and ultimately, early death. Worse, this is true even if you exercise regularly. To put it simply, being highly sedentary, as many of us are, is toxic.
What Inactivity Does to the Body
Let’s start with the healthiest people among us to use as an example. In one study, when highly trained endurance athletes were forced to bed rest, their aerobic fitness levels dropped by about 20 percent in just three days. What took them months to build was erased in a matter of a long weekend with no movement.
This isn’t unique to highly trained endurance athletes. If you took a regular, typical healthy adult and forced them to 40 days of bed rest, their heart would show changes similar to 50 years of aging. Now, this isn’t about missing a workout or two. Exercise only makes up a tiny fraction of your day. The toxicity comes from when movement begins to disappear from your life.
Why Exercise Alone Isn’t Enough
And this begs the question, why is exercise alone enough? A part of the answer lies in our muscles. Our muscles are more than just a machinery that power movement. They’re also really important for regulating things like our metabolism. Let’s use blood sugar as an example.
Our muscles are like sponges for blood sugar. When we regularly use and contract our muscles, they’re like a moist sponge, soaking up the sugar from the bloodstream. But when we don’t regularly use and contract our muscles, like a dry and shriveled-up sponge, not really good at soaking up anything.
Now, here’s the key. When we exercise, it rewets the sponge. But eventually, that sponge dries out if you get little to no movement the rest of your day.
The Tobacco Industry’s Unlikely Lesson
So what do we do? Well, we need to keep the sponge moist. Now, I’m not going to tell you that we need to move all day. Instead, I’m going to suggest that we follow the lead of an unlikely place, the tobacco industry.
(Laughter) In their early days, cigars were their primary product, but this was the industrial age. Millions were working in factories, and those workers only got short breaks from their lines, certainly not long enough to smoke a cigar. Thus, the cigarette became the primary focus of the tobacco industry, so that these workers could get their fix in small, short doses a few minutes at a time throughout the day.
And if sitting truly is the new smoking, as the saying goes, then what better way to fight back than to use the approach of the tobacco industry, but instead of smoke breaks, movement breaks. Short bouts of movement, a few minutes at a time, sprinkled in throughout the day.
The Science Behind Movement Breaks
If our muscles need regular use to function optimally, then outside of any exercise time, we need to be contracting them frequently through movement. The question that we asked in my lab is, what’s the least amount of movement breaks that we need in order to offset the harms of being highly sedentary?
And the answer, we found, was a five-minute walk every half hour. This reduced the blood sugar spike after eating by about 60 percent. That’s the size of the reduction you would expect to see if you put someone on medication to manage their blood sugar levels.
The cool part is that our participants weren’t sprinting or even walking fast. This was a stroll. They were walking at two miles an hour.
Putting It to the Real-World Test
Now, I want to be honest. What I’m proposing to you as the answer to our modern sedentary lives are five-minute movement breaks every half hour. The truth is that when I found out that this was the answer, I was disappointed. My immediate reaction was, “There’s no way people are going to do this,” largely because I couldn’t realistically do it myself.
And so part of me wondered whether this should be the end of the road for my research on movement breaks.