The first thing is to make sure that you are warm and dry. Any discomfort will be multiplied if you are cold or wet. Your gear also has to fit properly, not tight, or again this will make things worse.
After that its a matter of looking at how you are say, do you have enough room for example. The top box could be moved back, and adjustable pillion pegs are also available. Also are you being buffeted then a new screen might help
All worth a look.
Keith C