Pain. Did we mention that, the pain?

Traveling the Camino de Santiago as a pilgrim is often not a pleasurable experience, in the physical sense.

Heat, cold, rain, difficult terrain, average daily hikes of 26 kilometers (16 miles) — for the whole of a month, if you follow the popular route from the France-Spain border to the Spanish cathedral city of Santiago de Compostela, which covers nearly 480 miles.

Today, we battled through one of the more taxing legs in the final stages of the camino: From Palas de Rei to Arzua, which checks in at a daunting (for civilians) 30km — or 18.6 miles.

We needed no less than nine hours on the road to complete the trip, and one of us was close to collapse the final couple of miles.

This sort of thing happens all the time in Europe’s most famous pilgrimage. And those who wonder … “why do they do it?” … well, that is a fair question.

What made Day 3 of our Camino (Day 27 or 28 for those who started back in France) so difficult was the stage’s distance, the terrain and temperatures which zoomed into the 80s here in the northwest of Spain. (Rain can be worse; soaking the pilgrims, causing heat loss and turning the trails into mud.)

We had our itinerary weeks ago, and we always knew this would be a tough day. The longest day, as well as the third day — and doing it after the first two days had beaten us up more than a little.

The most common injuries on the camino are blisters, which can be truly alarming. But joint pain is a big factor, too: Bad ankles, wonky knees, recalcitrant hips. And, of course, aching backs and shoulders abused by big packs.

Why do people put themselves through that?

Some are lured by the test of body and soul. Some are deeply affected  by the theological implications of making the ancient pilgrimage to Santiago, where the relics of Saint James are found. Others are attracted by the chance to meet people from all over the world who are dreaming the same ambitious dream.

Few moments are fraught with danger or call for daredevils, but the whole of it makes it one of the toughest things most of us will do.

Since we are doing the short (five-day) Camino, we are not carrying those enormous, 10-15 pound backpacks. But that is not to say we were walking without loads — water, food, a guidebook, spare clothes, two types of glasses (sun, regular), layers of cold-weather gear, fanny packs, a smallish backpack …

The first 10 or so miles, to the town of Melide, where more than a few pilgrims called it a day, was not difficult. That was ahead.

As the temperature began to climb quickly, we began to move more slowly. Our pace of about three miles per hour fell, after over the final four miles, to more like one mile an hour.

I stayed back with our least experienced hiker, and she was fighting to keep moving from about 3:30 p.m. on, and I wasn’t doing much better.

Every ascent and descent was torture, and we had four sets of them, over those final punishing miles. Up a hill, on rock-strewn paths … a short period of level, rock-strewn ground, then the inevitable descent across more rock-strewn paths … and things nearly ground to a halt.

We drank lots of water, and I practically force-fed a Snickers bar to our climber who was about to bonk — as cyclists used to say.

So, why didn’t we just quit and call a cab? Get a ride into Arzua inside an air-conditioned vehicle?

Because the Camino de Santiago demands that peregrinos walk the entire distance to be credited with completing the pilgrimage. No wheels of any sort. No bikes, no wagons, no cars, no buses. All on foot.

Even by the third day, the desire to make it to Santiago on our own two feet is a powerful incentive. “I can make it. I can make it. But I have to rest. No, if I rest I will never get going again. No, I don’t want a cab.” (As cabs rolled past us on the final stages.) “Everything hurts. I feel like I am going to throw up. I can’t move. No, I don’t want a cab.”

Like that. And at some time it goes on with most pilgrims, and especially those 1) with limited experience hiking; 2) who are beyond prime hiking age of perhaps 16 to 50; and 3) those who are carrying injuries.

We saw, several times, two small women, one about 25, the other perhaps 40, pushing on and on despite both of them afflicted by bad knees. One knee one was so stiff that the whole of the woman’s leg was rigid as she swung it forward.

It hurt just to watch.

While waiting for our lagging and suffering member to make a climb in what was (we must concede) beautiful Galician farm country … I did some arithmetic in my head and realized that 30km is 18.6 miles, and around 18 miles is where even experienced marathon runners “hit the wall” — the point when continuing on becomes extremely difficult because the body’s reservoirs of energy are depleted.

It took nine hours, but we made it into Arzua. Our nimble companion had pushed on ahead (and her own condition was less than ideal) and the sweetest moment of the day was when we looked down the length of the main street and saw her standing and waving her arms at us.

She had one big beer. We were about to get two more.

Hours later, we are less than perky, and we can only hope our energy reserves return after a night’s sleep and a good, solid breakfast.

But we know this: It hurts to do the Camino de Santiago. Almost no one can go that far and do it day after day without exhausting their energy and/or sustaining an injury. Lots of people have to drop out, despite their greatest efforts — and often it is emotionally crushing.

Thank goodness, we are still in the fight, and the next two days, which should put us at Santiago’s cathedral, are not as long as taxing as the one we just (barely) finished.