I was afraid of the cold.

Saunas have been part of my life since I was a kid. Going to the swimming hall meant the sauna afterwards, and I was always the one who wanted to stay in longest. I was drawn to the heat long before I knew a single thing about why it might be good for me.

The cold was a different story. The cold I avoided for years.

Then my wife gave me a Wim Hof course. Not really as a gift — as a challenge. At the time I couldn’t last one second in fifteen-degree water. One second.

What happened next still surprises me. I ended up on a Wim Hof expedition, climbing a mountain at minus five in nothing but shorts. Two minutes at a time in ice water. Bathing in an ice river. An hour walking barefoot across ice.

Why I’m telling you this

Not so you’ll do any of it. Almost nobody needs to walk barefoot on ice. I’m telling you because the distance between one second and all of that is much shorter than it looks from where you’re standing — and because nobody dragged me across it. I just kept showing up.

It was never only the cold

And it was never only the heat. It’s the two together — the contrast — that does something neither one does on its own. That’s what All In is built around. Three rounds, both ends of the range, in a room with other people doing the same thing.

Don’t take my word for it

I plunge every day now, and I feel the difference in my life. There’s real research on heat and on cold, and you can go and read it yourself. You don’t have to believe any of it to begin. Come once. Sit in the heat. Get in the cold. Let your own body tell you what it thinks.

That’s the whole invitation.