The Hawthorne plant of the Western Electric Company, Illinois, 1955.

Researchers discovered that increasing lighting in the plant made workers more productive. Makes sense. Better lighting, better work.

But then someone pointed out a confusing detail: productivity also improved when they dimmed the lighting. In fact, making any change at all seemed to boost output.

What was going on?

The workers suspected they were being observed. So they worked harder. This became known as the Hawthorne Effect: the idea that the act of being watched changes the behavior of the person being watched. Also called the “observer effect”.

The takeaway is deceptively simple: measurement = motivation.

The Nike+ team saw this play out at massive scale. They had 1.2 million runners tracking over 130 million miles, and they found one number that mattered more than any other: five. If someone uploaded a couple of runs, they were probably just testing the app. But once they hit five runs, they almost never stopped. At five runs, they’ve gotten hooked on what their data tells them about themselves.

Aristotle said, "We are what we do repeatedly." He was just missing a number. Five.

I've spent the last year testing health trackers. Apple Watch. Whoop. Oura Ring. I wore all three at the same time for a stretch, which was as ridiculous as it sounds.

But I learned something from each one. And I think the choice matters less than people make it out to be. What matters is that you pick one and wear it.

Here's what I found.

Apple Watch (Series 11)

The Apple Watch is great at a lot of things that aren't health tracking. Finding my phone. Checking weather. Controlling my lights through Meross. Apple ecosystem. The activity rings do a good job of making you want to move.

As a health tracker specifically, it's fine. It gives you the data, but it doesn't really tell you what to do with it. And the sleep tracking exists but it's shallow compared to what else is out there. And the battery dies fast and you're charging daily.

If you want a smartwatch that also tracks fitness, this is the best option. Pro tip: I bought mine on Facebook Marketplace for $200, about 30% of retail.

Whoop

This is the one I keep coming back to.

No screen. It just tracks your body (strain, recovery, sleep) and every morning it tells you where you stand. The data is detailed in a way the others aren't. HRV, respiratory rate, skin temperature, blood oxygen, resting heart rate. All translated into actionable insights.

My favorite feature is the biological age score. It takes your data and tells you how fast you're aging relative to your actual age. I've been recovering from ankle surgery for a couple months, so mine is currently... unflattering. (Screenshot of my biological age here, don't judge.)

You can wear it on your wrist, bicep, torso, waistband, or calf. Battery goes 4-5 days, and the charger slides on while you're wearing it so you never lose data.

The downside is the subscription ($12-$16/month).

Right now I'm rocking Apple Watch + Whoop. Double-wristing, I know. I'm aware of how it looks.

Best for athletes and anyone serious about recovery and performance data. Get a free trial month here: https://join.whoop.com/33D15D48

Oura Ring

Great concept: a health tracker that looks like a ring.

The sleep data is excellent. Studies have shown it hits 99.9% reliability for resting heart rate compared to medical-grade devices, which is remarkable for something on your finger.

It wasn't for me though. The ring is bigger than you'd expect, and I felt it constantly. Washing my hands, lifting weights - if you lift, it's going to get scratched up fast. Battery life is solid (4-7 days), no mandatory subscription, clean app.

If you're someone who hates wrist wearables and cares most about sleep tracking, it's worth trying.

Now, does any of this actually matter?

Do you need to know your blood oxygen levels? Your heart rate variability? Probably not.

But that's not really the point.

The point is what happens to your behavior when you know something is tracking you. You get a notification that your recovery is low and you take the rest day. You see your sleep score tank after a late-night Netflix binge and think twice the next night.

It's the Hawthorne Effect, applied to your body.

And the research backs it up. A Lancet meta-analysis of nearly 164,000 participants found that activity tracker users walked about 1,800 extra steps per day and lost approximately 1 kg of bodyweight. The benefits were "clinically important and sustained over time."

Every device is going to be slightly off. But we’re looking at the trend line. If your resting heart rate climbs for two weeks, that's a signal. If your HRV rises after cleaning up your diet, that's validation built from awareness.

All three offer trial periods and return windows. That's how I tested each without spending a fortune. Buy one, wear it for 30 days, send it back or keep it.

The best tracker is whichever one you'll wear. The one that gets you to five sessions. The one that turns your health from something you vaguely think about into something you see, every morning, in numbers.

What's measured is managed.

Jacob · The Renewal