What happened there?

Today I took a late morning class, and I felt like hell going in. I was still sleepy and stiff, and I have been having a slew of digestive issues these last few days. Bleah. Just didn't feel like being there.

Have you ever started to watch a movie or TV program, and felt bored or disinterested at the beginning, considered turning it off? But then, somehow, you get caught up in the story, you're dying to know what happens next, and you've sort of lost yourself for a while because you're enveloped in this other reality?

That's was class was like today. I was so bored with pranayama. I was so not into trying to touch the ceiling during half-moon warm-up. I felt achy and cranky, and I wanted to be home, in my bed, with the covers pulled up. But somehow, I don't when or how, my mind floated out of that attitude, and I was just so engrossed in the practice that I didn't really think anymore.

How does that stuff happen? Can't I always be in that magic, non-thinking state during yoga?