I agree completely. Diet and low impact exercise/stretching are the big ones.
I was diagnosed with AS as a teenager and recall spending months at a time on crutches with swollen ankles and knees (having a fluid drained and replaced with cortisone injections), at times it affected my finger joints, and in my twenties and early thirties my lower back. Throughout most of these years, particularly early on, Naprosyn was my goto solution.
Up until about 2 years ago, I couldn't imagine getting a solid night sleep without some kind of lower back pain waking me, and putting my socks/shoes on of a morning generally involved sitting or laying on a bed and straining to pull my feet up to reach them.
I'm not big on swimming, but in the past couple of years have taken up regular Yoga and this has had huge benefits for my lower back (and state of mind).
Even more fundamental to this, I believe is my change of diet. Over the past couple of years I've (gradually) reduced my sugar, dairy and meat intake and adopted a more planted based diet. I didn't dive in at the deep end, but I'm now at the put where the only dairy I now indulge in is the occasional cheese, I eat virtually no red or processed meats, might eat chicken/fish once a week at most, and sooth my sweet tongue naturally with fruits, honey, etc.
My lower back hasn't bothered me for about 18 months, I can now put my socks on while standing and I rarely, if ever, suffer joint pain elsewhere. I feel more energetic, have taken up running (ran my first 5k recently) which is something I always thought would be something beyond my reach.
I don't like to preach or say any one particular thing (if anything) is going to change your particular situation. I can only say the improvement in my quality of life over the past couple of years has been significant since changing my diet and introducing some regular movement.
I'm going to miss the Chrome (IE9 too) combined search/address bar. No more will I be able to type in "haircut" or "bank" and have my browser know to kick off a search as there's no clear distinction from TLDs anymore.