I think our body clocks have something to do with our desire/need to cook. For example, when we're nearing fall and the temps begin to drop and the days become shorter, I long to get in the kitchen and surround myself with the fragrances of preparing soups, stews, etc.
Then cold weather time is here and I find myself in the midst of those delicious soups and stews but, now, I'm gazing forward to all the fresh produce that will grace the roadside markets and the grocery store when the weather warms.
Well, doggone it, we're never happy, are we?
When I find myself out of the "zone" I just go with the flow and realize that it will pass and, as others have already mentioned, I'll be back in the saddle again.