He made me lie on it but lengthwise so my spine was against it. I had to flatten out so that my spine touched it along it's length with my knees bent and feet and elbows and forearms on the floor.Just keeping this balance (very easy) has some small beneficial effect.
For one it was SO comfortable, I positioned it so that it ended at the bottom of my sacrum and because it is round it didn't really touch the painful spots. The exercise he recommended was simply raising my feet a few inches off the floor, holding it there for a few counts, alternating and repeating. Easy as! This develops a greater core strength.
I LOVED the roll and feel as if it would be ideal for just laying on for a while sometimes, watching TV for instance. It may not be for everyone but I can not see any negative points for using it with simple core strengthening exercises in mind.
There are so many exercises I can't do just because they require lying or sitting so the sore bits have contact
. I think this will help sort that out 
Helen
. Topically, I saw Dr. Greenslade only last week who recommended core strengthening (no Kegels of course), so thanks to your nephew, no need to look any further! The other exercises in the video could be useful for people too, I suspect the thoracic spine in a lot of us could do with loosening up, especially as we get older and less flexible. About the only flexible thing I have at the moment is my credit card! 
) but you did make me smile with that comment, in a twilight zone
and yes all of those people are still my friends but are all respectable (ish) now. We do have a great time when we get together but it is mainly about what we used to get up to all those years ago.