The race is six weeks away. Right on schedule, I hit a slump. It’s so hard to stay motivated during three months of training.

I ran 6.5 miles on Saturday and 8.1 on Sunday (don’t worry if you didn’t—my shorter weekday runs mean I have to cram in miles on weekends) and it left me pretty tired. Rephrase that: really tired. At the same time, I know I’m not yet ready to run 13.1 as fast as I would like. Tired, but not finished is a tough place to be.

I’ve been in this spot before so I know the only thing to do is to keep running. Stick to my schedule. This is one of the many reasons why running is a mental challenge. The real hurdle isn’t getting your legs strong enough—it’s getting your brain strong enough to keep your legs moving. It took a lot of mental stamina for me to keep running on Sunday when my legs felt like lead and I still had to get up and over the Brooklyn Bridge. And it will take a lot more mental stamina to keep hitting the road for six more weeks even though I’m already so spent.

One of the tools I use to keep myself going is a calendar where I mark off the days I exercise and what I did: if I lifted weights, if I swam, if I ran and how far. I believe it’s my single most important exercise motivator. I think of it as the way I hold myself accountable.

But it turns out that what is going on in my calendar may be a lot more complicated than I thought. If you believe the habit scientists (and yes, they do exist!), filling out the squares on my calendar is a reward that my brain has learned to crave.

This is from a fascinating article on habits in The New York Times Magazine:

“According to another recent paper, if you want to start running in the morning, it’s essential that you choose a simple cue (like always putting on your sneakers before breakfast or leaving your running clothes next to your bed) and a clear reward (like a midday treat or even the sense of accomplishment that comes from ritually recording your miles in a log book). After a while, your brain will start anticipating that reward — craving the treat or the feeling of accomplishment — and there will be a measurable neurological impulse to lace up your jogging shoes each morning.”

There it is—right there—“ritually recording your miles in a log book.” It’s a reward that my brain craves that has helped me turn exercise into a habit. I have a simple cue—I walk by the gym on the way to the office—and a clear reward, my beloved calendar. Such a simple thing creates meaning. At tough times like this in my training, when I’m tired, when there are weeks to go and it feels like the race will never come, I rely hard on these simple habits to get me through.

And on my friends and family. Thanks guys!

Read Jennifer's Training Week 1: Handling a Setback

Read Jennifer's Training Week 2: The Pros & Cons of a GPS Watch

Read Jennifer's Training Week 3: Finding Time to Train

Read Jennifer's Training Week 4: Strengthen Your Weak Parts

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