One Saturday several years ago, Walt and I decided to hike the Grand Canyon. We went down the South Kaibab trail to the bottom, meandered along the banks of the Colorado River, then headed back up to the top along the Bright Angel trail.

It’s a pretty big day: roughly 17 miles total distance, with a 5000-foot elevation gain. Not for the faint of heart. But we figured, what with being distance runners, what with being high altitude mountaineers, what with knowing for sure that we can do such a thing having done it several times before, that we were well within our capabilities.

Now, before we hiked, we hit the park services and asked them a few questions about our choice of trails. We explained our backgrounds, our athletic feats of wonder, and the ranger said that what we were planning to do shouldn’t be done. That each year, the park service has to rescue 375 people who get into trouble in a whole assortment of ways—dehydration, broken bones, exhaustion, squirrel attacks, elk mauling, sunstroke, and so on. I did some quick calculations: first responders had to rescue at least one hiker a day. In other words, climbing Everest would be safer.

Walt, of course, shrugged the warning off. I, on the other hand, wondered if we were being foolish. I’d hiked part of the Canyon before with my kids, nearly killed the three of us because I’d only thought to bring a single plastic bottle of water. To this day, they tell that story to anyone who will listen, a testament to my questionable parenting.

Maybe the ranger was right. Maybe we would spontaneously burst into flames on the Canyon floor, I mean, I do remember it being quite hot. Maybe after all that time in Ireland, average summer temperature 65 degrees F, I’d stroke out under the blazing sun. Worse, what if we didn’t make it back to the top to catch the last shuttle bus at 7:30 p.m., the one that would take us the three miles back to the car. I know what walking an extra three miles feels like after a big day, and that was something I wanted to avoid at all costs.

Would this be another one of Walt’s death marches?

We got an Alpine start, which means we were at the trailhead long before the sun came up. I’d forgotten to pack my headlamp, which is sort of bad when you’re going to trot down a mountainous trail in the dark. Walt had his, but he never looks straight ahead for very long. One minute I’ll see the next few steps in front of me, then suddenly, not.

I expected us to be the only nut-jobs on the trail but discovered that was so not the case. At 4:30 in the morning, we met a line of trail runners a half mile long. One of them mentioned that they did this loop every Saturday morning. Apparently, the ranger we’d spoken to wasn’t aware of this tradition. He was used to dealing with the general public, most of whom needed to be reminded to pack an extra bottle of water, slather on some sunscreen, wear a more sensible pair of shoes. Carry supplemental oxygen.

All along the journey, we spotted warning signs about the 101 ways we could make the wrong choice and die. At every intersection, we were given the option to continue ahead at our own peril or to turn around and head back to safety.

I suppose, when you deal with the general public, you’ve got to impress upon ridiculously stupid people.

The Canyon was magnificent. Not sure what else to say. The place took my breath away, particularly at mile 15, when I was ready for the hike to be done.

The whole experience got me thinking:

Who you hang around with matters. You can hang out with the Saturday morning trail runners who think nothing of mileage or elevation gain, or you can hang with the gift-shop crowd buying souvenirs and ice cream. The people around you determine your normal.

Anything worth doing takes effort. Writing a book, starting a business, completing a big, hairy audacious goal of any kind. You will hear about all the shit that can go wrong, which will make you question yourself every step of the way. It will prevent you from getting started. It will stop you the moment the exercise starts getting hard, and it will get hard. It will make you question your capabilities and your fortitude, in other words, yourself.

Know what will be required of you, what will make the job doable, what you’ll need to take along in order to be successful. Have a plan of action, ask the right questions, and then decide if the advice is applicable to you.