All Yoshihito Oonami wants to do is retire and give his worn body a rest.

Instead, every morning at 1:30, Oonami, 73, wakes up and drives an hour to a fresh-produce market on an islet in Tokyo Bay. While loading mushrooms, ginger root, sweet potatoes, radishes and other vegetables into his car, he frequently lifts boxes that weigh more than 15 pounds, straining his back. He then drives across Japan’s capital city, making restaurant deliveries up to 10 times a day.

"As long as my body lets me, I need to keep working,” Oonami said on a recent morning, checking off orders on a clipboard as he walked briskly through the market.