As a young southpaw boxer, Mike Mueller sparred with Muhammad Ali, then known as Cassius Clay, to help him train for the 1960 Summer Olympics where he won a gold medal.

But Mueller, a restaurateur, mostly kept that brush with fame to himself. Many family members learned of it only several years ago after someone presented Mueller with a gift, a framed poster of “The Greatest” standing over a defeated Sonny Liston. “That iconic photo,” explained Bryan Bach, a grandson by marriage. “Without batting an eye, Grandpa Mike goes, ‘Oh, it’s Cassius.’ Out comes this story. He was extremely humble and modest.”

A multisport standout at Hopkins High School, Mueller could have had a college athletic career. Instead, he married as a teen and started a family. He did find time for boxing, winning titles in 1957 and ’58 and the Golden Gloves Upper Midwest Middleweight Champion title in ’60.

At 25, with no restaurant experience, Mueller bought his first eatery, Hoagies, in Minneapolis and made it a success, later moving it to its current location in Hopkins. His motto was: “Just do it. Whatever you want to do,” Bach said. Mueller went on to open several other restaurants, including Lyn-Lake Cafe in Minneapolis, Gold Mine (now Gold Nugget) in Minnetonka and four Snuffy’s Malt Shops (still owned and operated by his family), inspired by a malt shop he’d frequented as a youth.

Mueller, who died Sept. 12 at 79 of heart failure, was a hands-on boss who inspired respect and loyalty. “He approached business as a coach,” said his wife, Shirley. “You’d get more than one chance. He’d say, ‘If you make a mistake, get over it.’ He just had that love of bringing out the best in people.”

Dave Sliter, who worked for Mueller for more than 50 years, starting as a teenage dishwasher and working his way up to general manager, described him as smart and loyal, with “a magnetic personality.” Mueller worked side-by-side with his employees and made each one feel like an important part of the team, Sliter said. “He wouldn’t sit in his office or stand around and give orders. He’d pitch in. He’d do dishes, help make malts. He’d do everything.”

Mueller was also a hands-on patriarch to his large blended family, treating his blood offspring and step kin with equal devotion. “He never thought of them as ‘your kid’ or ‘my kid,’ ” Shirley said. “From the moment we were together, they were our kids.”

Bach remembers Mueller as “a constant presence” at all his many grandchildren’s sporting events and performances. When one grandson had a track meet, Mueller rented a motor home and drove hours to Wisconsin so he and other family members could be there to cheer him on for his 23-second race, Shirley recalled. “That was Mike’s dedication.”

Several grandchildren ran track, and Mueller logged all their times in a notebook. He had a stopwatch and would challenge the grandkids to exercise — and tire out before bedtime — by running around the block. He announced each one’s finish, “Ladies and gentlemen, here comes ...”

Mueller was a fitness buff himself; he outfitted a home gym long before it was common, and was still punching a boxing bag into his late 60s.

Mostly he loved people, said Shirley, who suspects he chose the restaurant business “so he could talk to people all day long.”

In addition to his wife, Mueller is survived by his children Tracey Peterson, Renee Roble and Michael Mueller; stepchildren Christina Stark, Ann Bach and Peter Hanson; 21 grandchildren and 15 great grandchildren. Services will be held at 11 a.m. Sept. 26 at Mount Olivet Lutheran Church in Minneapolis. Visitation is 4 p.m. to 7 p.m. Sept. 25 at Washburn-McReavy Edina Chapel.