stretch

A regular stretching routine is essential if you have AS. It's the most important thing you can do to keep yourself as flexible, supple and to reduce pain and fatigue on a long term basis.

Because of this there is already plenty of good (and bad) advice out there for people with AS. I'll not repeat it here, but signpost you in the direction of some excellent resources by NASS (National Ankylosing Spondylitis Society, a UK charity):

Remember to take everything at your own pace, start slowly, and stop any stretch if you feel it causing you pain (you should only ever feel a slight stretching sensation).

Look for a local AS group who may be offering weekly exercise sessions with a physiotherapist, or ask to be referred to a physiotherapist who can explain each stretch in detail.

Make a list

Make a list of all the stretches you learn, and print out a 'cheat sheet' to remind yourself. Here's mine:

Standing

Look up / down  
Head tilt to side  
Chin tuck 
Look over shoulder  
Trunk side bend 
Reach up / down 
Pec stretch 
Hip flexor

Lying on back

Pelvic tilt 
Arm opening 
Knee rolling 
Knees to chest 
Double arm raises 
Bridging 
Angel wings 
Pilates clamshell 
Piriformis 
Hip abductor

On all fours

Cat stretch 
Pluto sniff 
Superman 
Twist and reach through 
3-point leg lift 

To finish

Tabletop 
Posture check 
Breathing