FORTUNE — This year, I kept my New Year’s resolution.

It was a resolution I’d also made in 2012 but failed to honor: to research, write, and pitch an ambitious, long story to a major magazine for which I’d never written. As a busy freelance writer, it’s tough to carve out time for this kind of speculative, uncompensated task when assignments are sitting on my desk that I know will bring in immediate revenue.

Laura Vanderkam already described the secret to my success in a Fortune article last week. She and I decided to be accountability partners and touch base weekly to report our progress toward our respective goals. As Laura wrote, she finished a long-standing novel project during the first 15 weeks of our partnership simply because she wanted to avoid the embarrassment of telling me she hadn’t met her 2,000-word weekly goal.

My path wasn’t quite as smooth, I’m sorry to say. (I console myself by noting that I haven’t written a book on time management like Laura’s 168 Hours: You Have More Time Than You Think.)

My self-imposed goal was to spend two hours each week planning and researching a magazine story idea. Sounds easy, right? I blocked off 2 to 4 p.m. on Friday, a slow time of week when few new work requests or emergencies pop up.

But the first week, the work I had allocated for Friday morning slipped over into the afternoon. I needed to field questions related to my volunteer role for the Parent Teacher Association. And, quite frankly, I was tired from a long workweek.

Once the clock slipped past 3 p.m., it hardly seemed worth it to jump into an enterprise demanding my creativity and brainpower. I found myself tying up loose ends from the week rather than embarking on a new project.

Discouraged, I reported back to Laura my utter failure to even spend two measly hours on my goal. She suggested moving the two-hour block to Monday morning, when I would be fresh and have more willpower.

It worked like a charm. My husband takes our girls to school on Mondays, so I could start work as soon as I showered off from my 6 a.m. yoga class. I found that working on the project from 8 to 10 a.m. still gave me almost a full day of regular work. I didn’t have the anxiety and pressure I felt on Friday afternoon, trying to wrap up everything before the weekend, while also diving deep into a complex project.

I also found that by putting out interview requests on Monday morning, I received responses throughout the week and was able to field them in between my other work responsibilities. This ended up putting me over the goal of two hours, just due to momentum.

Within a month, I had finalized and sent out one magazine pitch. When that was rejected, I turned to another project while I looked for a new place to pitch the first idea. In another six weeks, I had enough material on the second idea to send it to a magazine editor who seemed a good fit.

Granted, Laura ended up with 80,000 words of a novel at the four-month mark of our partnership, and I ended up with one 912-word story pitch and one that clocked in at 858 words. But I’m not ashamed of the comparison — I don’t mind being slow as long as I’m steady.

Looking back at the first four months of our accountability partnership, I can draw three clear lessons that may help anyone else interested in trying it out.

Understand your biorhythms

My initial stab at blocking out two hours for special projects failed because I picked a time of day and week when my willpower and energy were both flagging. It turns out I’m not unusual. As Laura points out in What the Most Successful People Do Before Breakfast, researchers find that resisting temptation once leaves us with less ability to exercise willpower subsequent times. Indeed, most failures of self-control happen late in the day, whereas in the morning, our supply of willpower is fresh.

Check in regularly

Both Laura and I have written on time management and productivity. We should be able to — ideally — pick specific, measureable, achievable, relevant, and time-bound goals. The missing link for me was to check in as often as the time frame of my goal: weekly. Before connecting with Laura, I’d tried telling my long-standing writing group about my two-hour weekly target. But the group only met once a month, so I didn’t feel regular pressure to meet my mark.

Find the right accountability partner

I realize that not everyone is lucky enough to find an accountability partner who also happens to be a time management expert. But you can choose someone as motivated and disciplined as you are — ideally a bit more disciplined than you. Before this experiment, I had a writing buddy who was supposed to check in with me every week, but she let the deadline slip … and then I let it slip … and pretty soon we were barely talking once a month. I’m pretty sure Laura won’t let me get away with that kind of slacking.

Katherine Reynolds Lewis

Stumbling towards productivity