I recently took a few days off between jobs, and I thought, “Hey, it would be fun to run a marathon while I have some time on my hands, just to see if I can!” I haven’t been training for a marathon, but I have been running, and I’ve run long distances in the past.
On the first day of vacation, I jogged from my house to a nearby lake that is about five miles around, figuring I’d do laps until I got to my 26.2 miles. But just after I passed 13 miles, I was out of energy and walked home with only a half-marathon to show for it.
On the last day of vacation, I decided to give it one more try. Now, one of the principles that I’ve learned from behavioral science is the value of commitment mechanisms, whether it’s a savings account that restricts access once you make a deposit (which increased in savings in the Philippines), committing in advance to a financial loss if you don’t quit smoking (which decreased smoking in the Philippines), or letting farmers pre-commit to purchasing fertilizer (which boosted fertilizer use in Kenya).
So I found an 18-mile trail near my house, parked my car at one end, and ran 13.5 miles in one direction. At that point, I had few alternatives to running the 13.5 miles back to my car. It’s true, I could have run the last 5.5 miles to the other end of the trail, but it would have been a pain to get back to my car. I also could have walked, but that just would have meant hours of walking in the cold with a dying phone and few supplies. (This is what Bryan, Karlan, and Nelson call a “soft commitment,” where the consequences are principally psychological rather than economic.) So I jogged back. Slowly, but jogging all the way. I made it back to my car just as my phone told me I’d clocked 27 miles.