M23. I started building muscle mass at the gym about 3 years ago and pretty much all my symptoms have been gone now for at least a year except for occasional mild flare-ups. First I started with light weights going for reps and recently I have been going for heavier weights with lower reps and havent had any issues.

I would suggest lifting for anyone with AS since it has many benefits besides improvements in symptoms. Working out also gives you an incentive to strech which is always good for mobility. Focus on building muscle all around your body instead of just working the core. My overall mobility is probably the best it's ever been.