I believe that it is a feeling we all have. To link it to the post of yesterday, you can say that although you can go a long way doing things that are fun, you will inevitably run into days when nothing is fun and you feel that you might as well have stayed in bed.
I think the secret to making the most of something that more or less feels like a law of nature is to accept that there will be days when you feel like a total loser - the important thing on those days is to keep from self-pity and self-blame, but instead remember that there will be other days: days when it's the part of its personality that's so amazingly unstoppable who's winning - and promise oneself that when those days come, it will be time to go with the flow and forget about the time and place while the tasks more or less solve themselves. As it is written in the old song: "Sometimes you're the windshield / Sometimes you're the bug"
And then it turns out that even if you cut yourself some slack when you're in your total loser mode, you'll more than make up for the lost effort on the days when you're in flow.
(Translated from Den gamle sang om forruden og insektet)