It's one of those days when things seem to exist merely to bug me. The rain (yes, even though I usually like rain), the traffic, the sticky mess on the hotel table where I set down my laptop. Not to mention my little walk directly under a gushy downspout, my tug of war with a sluggish computer connection, my lunch of dried fruit which has gone bad. Not to mention the fact I walked in late to the conference I'm attending. (And I hate walking in late.)
Complaining is an infection you can't seem to stop once it starts. The only way to reverse it is to notice you've got it. Step outside your complaining and acknowledge the pettiness of your complaints. Accept that the day is going to be what it is regardless of what you have to say.
In the same way, when you step outside your writing, you rise above whatever complaints or annoyances you might have. See where you are with your work, but don't fuss about the traffic in your mind, the rain of bad language, your current plot dilemma. Simply pay attention, observing it all as if you were a neutral party to your own creative process.
(If your writing is going well--great! Yet even these great writing days present a challenge. More on that later.)