Casting on ... falling short

My grand plans to have a giant orgy of casting on fell flat. See, I joined a new gym and last night, I decided a good way to work off the stresses and angst of the week would be to go to a step aerobics class, which I like.
I don't know what Reebok and the general step aerobics community have been up to since I last took one of these several years ago, but I think they've made it harder. The steps seem to be higher off the ground, the music seems a little faster, and the actual routines are much more complicated and need three or four feet to execute properly.
So when I finally settled down with yarn and needles to cast on a baby hat, I discovered the secondhand yarn was mysteriously worn in spots and wasn't that great anyway, and what I really wanted was the ball of red cotton, but it was all the way upstairs and I was all the way downstairs, and I wasn't going to run up *more steps* to get the yarn and then return to the couch via those same steps ... not so much.
(But I have a ball of Austermann Step in my work bag and two circs and 'Favorite Socks,' and I think I'll make the ones on p. 93 for the Fool, maybe start them today at lunch.)