I find myself slouching at my sewing machine alot, and I do have back and shoulder issues so my back and shoulders hurt like mad, I have one of those magic bags that drapes around your neck, and I use a lot, I even take it to retreats with me.
My shoulders bother me more than my back when I'm at my computer, I've been going for massages alot this year, but still struggling with them both, god I hope it gets better soon. I'm thinking I might need to go to the Dr. and see about getting refered for phyiso.
I also use the doorstop under my machine, and I think that does help a little too, also have one of those whoopy cushions and I can't sit on it for very long, it seems to aggravate my back more than help it.
I also am very short about 4'7" so I found that having my foot stretched out on the foot peddle was really hard on my siatica, so I have a little foot stool that I have my machine peddle on, I also have enough room to put my other foot on the stool, this does keeps my hip from hurting. I also have a small footstool at my computer and both feet are on it, it's definately not fun being short :cry:
I also have one of those weighted harness's and I do think it helps, just have to remember to wear it... :lol: