Meghna and I are working on a running a project, training up for a 24 hour challenge devised by the evil genius at Yeti Trail Runners. The distance is 30 miles, but it’s broken into 5 mile segments. You run 5 miles every 4 hours for a full day. Shampoo. Rinse. Repeat.

What you realize pretty quickly as you plan for this event is that it is, in many ways, harder than just running 30 miles. You know your body doesn’t love stop/start efforts. You know you have to run in the dark, at least twice. You know you have to run twice on short sleep. And you know you’re burning 24 hours, rather than the 6 or 7 it might take to do all 30, on trail, in one run.

So we’ve been doing longer and longer runs, mostly on Sundays. This last week, we had planned 16 and ended up with 19 (story here), which is fine. It’s all gas in the tank for the big day.

The more I run past the 10 mile mark, the more familiar I get with the rhythms of long runs. I think we ran close to 15 half marathons (or longer) last year. This year there are 4 or 5 in the bank already.

And so I see that, for me, there are these milestones in each long trek where I begin to understand how it’s going to go, the five mile mark, and the ten mile mark. The five and dime, if you will.

The first five miles are filler. My body is settling. My mind is clearing. Hopefully I’ve found my rhythm by this point. Then I’m into a stretch where I need to think about fueling. What I eat between 5 and 10 has a big impact on how things go beyond that. Pacing becomes important. Once I’m in that good groove, I have to be careful not to run too fast. I’m probably feeling great, but I have to resist the strong urge to run that euphoria, because things can turn tragic if I burn too many matches this early.

If you’re running 15 miles, it’s important to know that 7.5 is not really the halfway point, in terms of effort. You don’t reach the mental midpoint until you hit 10.

That brings us to everything after 10 miles.

That’s a fuzzy number, because really, I can run through 10 miles feeling good, without hitting that first wall of fatigue. But starting at about mile 10, I know the wall is coming. Correction. It’s not really a wall, more of a dip in flow. My legs begin to tire. My mind grows a bit cloudy. I’ve done a lot of work, and, if I wasn’t training for endurance, this might be the cue to stop.

My fuel and hydration effort now yields its consequences. If I’ve done things right, this little dip can be corrected with some fast calories. I hit a gel, and within about 5 minutes, energy levels rise again. I’m not fresh as a daisy, but I am able to maintain endurance pace, to manage the fatigue settling in, and to keep going.

That was particularly important on Sunday, when we hit our goal distance and still had 3 miles back to the car. Out there past the 10 mile dip, I reach a limbo state. My body is on autopilot really. Bodies in motion tend to stay in motion. My mind is floating too. I can’t conceive of how much farther I have to go. The distances are warped. Something in my head spurs me on, as if I can sprint to the finish and get it over with. I have to remind myself that I don’t have that gear to call on anymore. So I float there. Just running. Just running, until, improbably, the car appears, and against all instincts we just stop.

I never don’t wonder how much more I have in me, and it seems like a real waste of 19 miles of running, not to see where the real finish line is. I’ll have to run 19 more miles to have this shot at self-discovery again. And yet. Discretion remains the better part of valor. In a few weeks, I’ll set my alarm for 2am, and begin the process of discovering just how hard a hard thing can be.