Neck and shoulder problems from too much sewing ☹️

Oh no Alison, sorry to hear that! I definitely have to catch myself clenching my shoulders up towards my ears when I'm sewing. Defiitely look into what the best height desk and chair is for you, other than that I would say set yourself a 20 minute timer whilst sewing and take some stretching breaks just to make sure you're relaxing your muscles

I have neck and shoulder issues because of a disability. I find that I have to adjust both table/desk and seat. A good adjustable office chair with a higher back rest is great. 
as Hayley says, put a timer on, start with 10 minutes and build up to 20. After that time do some stretches in your own ability for hands, neck and shoulders. YouTube is good for things like that. 

I put rubber door stops that slope under my machine back so it slopes the machine higher in back than front a bit allowing me to have better posture instead of totally bent over the machine.  That has helped tremendously. They make a tilt table for machines but I'm cheap. 😝. I got 4 for a dollar or so at the dollar store.  They have them on Amazon as well.   Also setting a timer to take frequent stretch breaks. 

I'm quite short, so I bought myself a Horn sewing chair. It wasn't cheap but it is fully adjustable and has really helped. I also have my old office footrest which I use to raise the foot pedal on the sewing machine.