I think there is a difference between "I can't " and "I won't"--sometimes the latter masquerades as the former. We had one fellow who started ten years ago who "couldn't" roll but kept at it (with a LOT of encouragement and breaking it into pieces) and is happily rolling at age 57 today.. it took him almost nine months to get it. Some of us are training with physical disabilities and it can be a struggle to modify technique to adapt to what the body can do--on the other hand, if it's the mind which is causing the disability it can be almost impossible to change. We get a lot of beginners in our dojo who spend a lot of their first few trainings saying they'll never get it, but are usually moving joyfully after a month or two. But if they don't have a willingness to try, they never do... I like the adding "yet" to "I can't"-- I'll add it to beginner's class.