ah, tim reminded me, before the flector patch, from 2008 til recently, had to give up climbing stairs, up or down bothered the SI joint for me. now i still take the elevator more than the stairs, sad really, i was always a stair climber for the exercise, but my SI joint no longer enjoys the activity.
along those lines, gave up swimming, i think it was the breast stroke kick that was doing it, and i just liked that kick too much to get in the pool and resist, but now on the flector patch, have hopes of swimming again. it really was the best overall exercise, absolutely devine for my upper back, back over all.
sitting, oh yeh, even now, if i sit too long, feels like a mule kicked me square in the butt, and have to have a flat chair, as tim said, sloping in or back really bothers me.
laying, for me, if i lay on either side for even 5 or 10 minutes, it bothers my SI joint. for me its on my back with legs on pillows to give me a pelvic tilt, take pressure off the SI joint and lower spine. the only position i can sleep in. with a thin feather pillow for my neck.

but can't lay for too long, then my pelvic area (and spine) are all tight and stiff and prone to irritating once i'm up. lately, when i fall asleep in the recliner for a few hours followed getting up and then going to the bed for few hours, that seems to be the best for my SI and spine.