Yep, altering position, holding a conversation and other such distractions really don't go well with welding.
It's well worth getting comfortable before you start, and try to visualize where the rod hand will need to go and make sure nothing will restrict it, such as the torch cable.
I find that if I can't get comfy (awkward angles, aching knees, pain etc), then the weld will probably be rubbish.