It really depends on how sick I am. If I'm too sick to drag myself to my real job, yet I feel well enough that I can sit up, I'm usually working on my comic. It'll take my mind off how I'm feeling, and if I start to feel really sick I can still go an sleep for a while (thus not going into work).
But if I'm feeling so sick that all I can really do is sleep, then I throw on a movie and pass out to it. My comic can wait. If I were to work on it in that state, I wouldn't be producing any type of work that I'd put out so what's the point?