It's important to stretch while you're beading. Lately, I've been suffering from very sore shoulders, which I think are my rotator cuffs, possibly rebelling at how much bead embroidery I've been doing lately. Or it could be an ergonomics issue, with the way my keyboard is set up at work or at home. Hard to say for sure, I just know my shoulders have been pretty darned sore. I'm going to avoid beading this weekend (if I can, it seems hard to imagine not doing anything for the entire two days!!) and see if that makes a difference.
At the Techniques nights at the Toronto Bead Society meetings, Marilyn Parker always stops the session after about half an hour or 45 minutes to lead everyone in stretching exercises, which always feel really good! I really should start doing that on a regular basis when I'm beading on my own.
The funny thing was, Rachel replied that she was using the timer for her morning tea, which needed to steep for 5 minutes. :)
Although she did advise that she tends to stop and stretch, especially her wrists, whenever she changes thread in a beadwork project. Not a bad idea, except that it seems to take me a long time to finish a thread if I am working on an embellishment, more quickly if I am making something out of square stitch or peyote. But it's definitely a good practice to stop every little while and stretch, take a little walk, do what you need to do to give your body a little break from the focused beading, whether you do or don't use a stopwatch.