Before a long session I make sure I eat really well for about the week before hand, may sound daft but a good diet does wonders to get you over the bulk of it. It’s one of those areas that I don’t talk much as I’m keeping myself in a relaxed zone, completely relaxed. A bit like the back it’s hard not to push against the neddles so your body is usually naturally tense.
Basically, eat well, fruit and veg etc. Drink loads of fluids and try to hold your mind on something else. If you sort of make a joke of the pain to the artist in a way of letting him know you’re suffering and need to get medidative he’ll be aware what you’re going through and probably keep it to quite a quiet sitting.

Good luck!!
It’s gunna hurt whatever you doto be honest, just push through it.:)