And he routinely fools people into thinking he's actually a few decades younger than he is.

"I get that all the time," Sillari said. "I was at the doctor the other day, and they always ask your birth date if they don't know you. I told the woman, 12/22/15, and she looked at me with a half-grin. She thought I was teasing her."

Said Carlson, a long-time neighbor: "He doesn't look his age when you see him."

And he doesn't plan on acting his age anytime soon, either. Sillari said he will probably continue the daily walks until his legs betray him, which doesn't appear on the horizon anytime soon.

"It's where I do a lot of my thinking," Sillari said. "It's amazing, the things I think about."