Three years after quitting high school at age 16 to work full time, Mingo became Marsden Building Maintenance’s youngest-ever district manager. He then worked his way up the ranks until, at age 42, he was named the St. Paul–based company’s CEO. Under his leadership, Marsden Holding has become one of the largest privately owned facility-service providers in the United States. For the past three years, Marsden Holding has had record growth in income.