LOL!
This is kind of in response to someone else who mentioned having fribromyalgia and how you have to knit for short periods rather than long stretches of time.
I too have fibro. I also have some problems with my memory, or at least I must have because I put my knitting down a few minutes ago after knitting for about two hours. I couldn't figure out what was wrong with me, why I was so tired and ached all over. D'oh!
Half an hour, maybe an hour at a time is more than enough, especially when it's hobby knitting and not knitting for a deadline. ;-)
Murielle