Yesterday started off as a very unproductive day for me.

There was no obvious cause. I’d time-blocked my day as I always do, but I found myself unable to focus on even the simplest task, let alone anything particularly challenging or important.

Who knows why. I hadn’t slept well the night before, and I’m just coming out of a weeklong illness—either issue could be to blame. But regardless of the cause, as lunchtime approached it became clear that I wouldn’t be able to finish everything I’d planned to do that morning.

What do we do on days like this?

Any productive person has bad days. A morning starts badly, and as the day wears on, we feel worse and worse about ourselves. Eventually, we might feel that even if we start now, we’re not going to be able to make much of the day, on the whole. “Why bother?” we say to ourselves. “Even if I have a productive afternoon, I can’t make up for this morning.” This is not a useful posture.

Instead, we must let go of the past and make a new plan for the time that remains. A plan is not a promise—the point of any plan isn’t to follow it slavishly, but to always have a good plan for the time that remains.

Mid-afternoon, this is exactly what I did. I pulled out my journal and wrote a few lines about how frustrated I was with how the day had gone. Then, still journaling, I gave myself a pep talk and examined the time that remained. I had a couple of hours to work with, so I turned my attention to email and a few other low-friction tasks. After a few minutes, I picked up the pace, and at quitting time, I’d completed an acceptable amount of work for the whole day. Below average, yes, but acceptable. By sprinting to the finish line, I’d made up enough ground to redeem my earlier failings.

But until I let go of my guilt for how poorly the morning had gone, I wasn’t able to rescue the afternoon. Before we can grab on to the new plan, we have to let go of the old one. This isn’t easy, but it’s necessary.

And it works.