Title basically explains it.
My guy will ride once in a while with me but is only open to walking. He says it's the only gait where he doesn't get knocked around. I put my trainers really comfy western saddle on Caleigh and he said it only saved his "boys" a little bit. A canter is preferred over the trot if he's going for anything faster than a walk however he's not confident to try it off the lunge line.
He is rather stubborn though. He wears loose fitting jeans and loose boxer shorts under them. He can't wear tight fitted underwear or jeans because he feels tied in and claustrophobic. Should I buy a really soft seat saver? Or an athletic cup? Haha. He said he'd be more willing to ride if he didn't get smashed around so much.