If the pieces are small enough, I prefer sitting down. I have a nice 12" X 18" cutting board that turns (it has nice ball bearings in it) that works great and I can cut for quite a while if I'm sitting down. I also use a sturdy tray - cost about $20 from Lowe's that is large enough for this cutting board. (It's a cutting mat glued to a board - real nice - picked it up at a yard sale!)
If I have to cut strips/borders, I use my cutting table but get the dreaded burning in my shoulder blades. I usually just cut one or two sets at a time and do something else for a while.