Raised in an Amish family, Miller graduated eighth grade, then went to work on the family farm and later became a carpenter.
He enrolled in Chicago's American School in 1962, but had to drop out when the birth of his children who made life too busy.
Miller returned to his studies last year while still working at Willie's Cookbook Homes -- a job he has held 45 years.
Next month, Miller will walk down the aisle to collect his high school diploma.
"Education is important," Miller told the Elkhart (Ind.) Truth newspaper. "You're never too old to get educated."
Next up, Miller said, are classes in computers and Spanish.