Do you realize that you can work your abdominal muscles while you are knitting hats? I have gone to many knitting groups to speak and have seen slumping bodies in chairs and on couches. I have heard complaints of lower back discomfort and shoulder and neck discomfort. I am going to help you get rid of your lower back discomfort and help you work your abdominals at the same time you are knitting.
First thing is posture. Plant both of feet flat on the ground. If your back is not touching the back of your chair then you can use a small step stool to prop your feet up and sit all the way back or place pillows behind your lower back so that your body is moved forward and your feet are touching the ground. With weaker lower back muscles you need to strengthen your abdominal muscles.
Sit tall and elevate your ribcage. Some of you may feel a pulling in your abdominal muscles. This is normal and means that your abdominal muscles are tight. While you are sitting tall pull in your abdominal muscles as tightly as you can. Keep on breathing. See how long you can hold in your tummy and breathe at the same time. Can you get through a whole row of knitting?
What will end up occurring is a mental awareness of better posture (keeping your rib cage elevated) and keeping your abdominal muscles tight. The more you tighten your tummy and hold (isometric exercise) the better your abdominal results will be.
So knit away and have fun but remember to sit tall and tighten your tummy. As time goes on this will become easier and easier for you to accomplish. When you start out you may not be able to hold this contraction for long. Time will pass and you will be able to hold the contraction of your abdominal muscles longer and even tighter which will work your abdominal muscles even more intensely.
More Stretches to follow.