“Why are you so obsessed with death?” Geoff asks me as we walk back to the truck. We’d been looking for elk that morning. It hadn’t gone well.

His question sticks to me like gum on the bottom of my boot because I’d never realized that’s how my writing lands with people.

I don’t know Geoff. This is the first time we’ve hunted together. And he only knows me from The Mountain Project videos and what I’ve written on our website and emails. He’s smart. And I like that. I like his question.

“It’s not death that interests me” I reply, “I’m interested in time.”

Specifically I’m interested in making sure I don’t run out of time before I’ve lived all the life I hope to live. I’m keenly aware of the finitude of my supply of time. I’m keenly aware it could be any day that I come to the end of it.

Time is a strange thing when you think about it. We experience time as the passing of days, the ticking of a clock, and in that regard it’s not strange at all. It flows like a river from one day to the next.

But that’s not how time works. It’s stranger than that. Like the complexity of a river’s fluid dynamics, time flows at different rates and speeds—it has ripples and rapids and eddies and pools. Moving water is dynamic and so is time.

Time passes slower at sea level than it does on the mountain top. Highly sensitive clocks can measure this.

If your wife goes on a vacation to the beach while you’re hunting tur in the Caucasus, when you reunite, you will have aged more than she has. For you in the mountains, time seems to pass the same as if you were on the beach, and vice-versa for her. You don’t notice the difference because time flows differently only relative to other’s experience of it. We only notice the difference when it’s brought back together in space. This is weird.

Life comprises a series of granular moments—moments of change, constant change. And those grains flow through the hour glass one to the next. Each of us has an hour glass we’re working with, but we only see the bottom half of it. We don’t know how many grains of moments remain to fall through.

Whether I’m on the top of the mountain hunting, or playing on the beach… the real question isn’t how fast time moves—it’s what I do with each moment as it passes. The physics of time is confusing, confounding, and fascinating (I highly recommend Carlo Rovelli’s book, The Order Of Time). But it’s the philosophy of time that matters in our day to day.

Understanding time’s finitude has changed how I approach each day. I no longer put off experiences I want to have, conversations I need to have, or the love I’m here to share. I’ve stopped treating time as an infinite resource, an asset which will not run out in either this life or one to come. I do not sacrifice today on the wish of a better tomorrow, whether in heaven or somewhere else.

Instead, I approach each day with intention. If time is the measure of change, and everything is always changing, I’m going to direct that change as best I can.

In the morning I wake up and make a cup of coffee. Then, I plan my day. I connect my actions to my long term goals. It’s the accumulation of granular actions during our granular days that build the memories and the life I want to look back on having lived.

I’m working on a video that touches on this idea. While editing, I look back on hunts from eight, nine years ago. We were young. Life was different. My beard was black. Chase was skinny. Those memories are invaluable.

Nothing I write is about living in fear of death. It’s about living with an acute awareness of life and the passing of time. Every choice to spend time on one thing is a choice not to spend it on something else.

So I choose carefully.

I choose the pursuits that fill me with purpose and I choose the people who fill me with joy.

Time may flow differently on the mountaintops and at sea level, but wherever we are it is flowing. So the question is, How will you fill your moments today?