I'm sure I can come up with lots of reasons as to why the run was bad (and by bad, I mainly mean slower than I've run in a long time). I was sore from doing some work around the house earlier in the week; I had also done two hard workouts that week; I gave blood a week ago, and it always takes my body some time to get back to normal after that; it was raining; I've only been back from a two-week trip to England for two weeks, and, while I ran there, I didn't do the serious running I do here. I could go on, but you get the point.
Whenever I'm having bad runs, I usually have two thoughts that comfort me. First, I know that I'm out there and no one else is (or at least no one I saw). Most recreational runners see the rain, and they stay inside, while I'm out there slogging away. I used to think that during really early morning runs, as well, when I would see people just beginning to move around, lights coming on in people's homes (often blue-ish lights from the television, actually). But that was before I learned to like early morning runs. The second thought is that I'm not running for today; I'm actually running for January or February, that time when I am doing the serious training for the longer races I like to run when I'm able. Today's run might be bad, but putting in the time will help me in the coming months.
It was that thought that led me to think about writing. Those of us who try to sit down on a regular schedule and write, like those of us who run on a regular schedule, have bad days. We don't know where the story is going or how we're going to do anything poetic with the one image we have in our heads, and we sit there and look at the page or screen. And we sit there. And we sit there. It's days like this that we wonder if we shouldn't just wait for inspiration to strike and only write on those days.
However, we don't write for today any more than I run for today. We write so that a month from now or a year from now, we have a draft of something to work with, to make better. I once heard Ted Kooser talk about his writing process, and he said that he sits in the same recliner every morning from about four until seven or so. He said that six out of seven mornings, he doesn't produce anything worth keeping. But one out of those seven will lead to something that just might work. He believes he needs the other six days to have the seventh. He's not writing for those days; he's writing for the future.
Whenever I sit down to work on whatever project I'm in the midst of, I try to remember that the draft of the poem or story doesn't have to be perfect, that I'll have a future to hone it and make it stronger. But I need those bad days of sitting there, writing things I know are not very good, because I know that they will get me to somewhere better, or at least give me something to work from later. A month from now, perhaps, I'll be looking over the draft and now see where I should go with that image or character. Or, just maybe, I'll read something I wrote today and I'll think, "That's not bad." That's a good day.