Many of these things can be abated by having a bit of room to move and inactivity and confinement can exacerbate them.
This is blunt answer, but you abate the problem by paying for a seat in a premium cabin. There's no other way around it.
The check-in or gate agent may help by trying to get you an aisle or bulkhead seat in the same cabin. I think that's the best they'll do for you.