World's oldest practising doctor, 100, says, "Retirement is the enemy of longevity!"

Meet Dr. Howard Tucker, who just turned 100 and is profiled in a great article here. A neurologist, he holds the title of “World’s Oldest Practising Doctor,” per the Guinness Book of World Records.
He’s been practicing medicine for 75 years. Though he recently stopped seeing patients, he still teaches medical residents at St. Vincent Charity Medical Center in Cleveland, Ohio.
He’s outspoken in opposing the whole concept of retirement. Here’s the money quote:
“I think that to retire, one can face potential shriveling up and ending in a nursing home. It’s fun staying alive and working. It’s delightful work. Every day I learn something new.”
Okay, but aren’t some jobs too physically onerous to keep doing after a certain age? Tucker concedes the point, but gives only a little ground. “I don’t understand it. I don’t understand golfing three days a week. I’m going to caution [people]: if they retire from their work, they should at least do something as a hobby, where it be communal work or self-hobbies … you need a stimulus for the brain daily.”
The doctor’s been up to a lot recently, including taking up snowshoeing, as a substitute for downhill skiing, which his family wanted him to stop after a neck injury. He’s also made sure to keep up with the latest technology.
In other words, he’s still thinking about the future! “I think I’ll live forever, knowing that it’s not real. But I feel that way. I never think of death. You die once, but you live daily … focus on the living.”