I’ve been rereading Endure by Alex Hutchinson, a book that dives into the science of limits. He weaves together research from endurance athletes, polar expeditions, ultra-marathons, and deep-sea divers to explore one simple question: What actually determines how far we can go?

He argues that endurance isn't just about what your body can do, but how your brain interprets the signals your body sends. He names it a “mind-body threshold”, where perceived effort, motivation, and meaning sway whether we push on or pull back.

I’ve been training for the Baltimore Half Marathon. Normally, I run in the evenings once I’m warmed up and the day’s energy has kicked in. But yesterday, with college football later in the day, I set out earlier than usual (okay, 11 am, but for me, that’s early).

Right from the start, I wasn’t feeling it. My back was stiff, motivation low, and a lingering head cold kept nagging me. From mile one, it already felt like it was going to be harder than usual.

The book has a chapter about perceived vs. expected difficulty: how our internal story can make us feel doomed before we even hit the real hard parts. I caught that voice creeping in… “this is going to be brutal,” “maybe I should reduce my goal.”

Instead, I shifted perspective: “this run isn’t about speed, it’s about mental perseverance.” If I didn’t stop short of my goal, I’d build toughness by practicing what it feels like to keep going when conditions aren’t ideal.

I picked a lofty target of 13.25 miles, with grace that if my body — not just my mind — truly told me to stop short, I would. As the miles added up, my muscles loosened, I found a groove, and I sped up. Around mile 10, I hit a wall. I asked myself if it was my body telling me to quit or my brain. I reminded myself this was the training.

So I leaned into that frame and kept going. I distracted myself by counting how many more songs I would listen to before I was done. When my tracker hit 13.25, I had a new personal best: 1:51:14.

Not because I chased time, but because I gave myself a different goal. I focused on mental endurance instead of physical. I chose to see the challenge as an opportunity to build capacity for the days when conditions are ideal.

That mental shift doesn’t just apply to running.

It applies when your project hits roadblocks. When the week feels heavier than your energy. When motivation dips and you start wondering, why am I even doing this?

Of course, this isn’t magic. You don’t reframe your mindset once and suddenly overcome every obstacle with ease. Some days will still feel heavy. Some runs will still feel slow. Mental endurance doesn’t erase difficulty; it just gives you a better way to face it. It’s work. It takes repetition, patience, and a willingness to keep showing up even when progress isn’t obvious.

In those moments, the goal sometimes isn’t to perform your best. It’s just to keep going long enough to remind yourself that you can.