About 5 years ago, when she was about 77, my mom's knees were really bad. She had an arthroscopic surgery on one of them, but was still hobbled. So I got her a wheelchair on her transit at Heathrow, even though she imagined she could have suffered through without it. She said it was amazing. They were whisked from the plane, through back doors, quickly though transit lines - - it was fast and fantastic. I've offered her this again, but her knees have improved, and she doesn't just want to try to fake it.