At age 47, Bishop-designate Hennen will be the youngest bishop leading a U.S. diocese. In 2020, he was appointed vicar general, and in 2021, pastor of Sacred Heart Cathedral. While he said he appreciated his role as vicar general, parish ministry is life-giving. He described the role of vicar general as being a sounding board for the bishop and handling some of the challenges in parishes that the bishop delegates to him. As vicar general, he also has opportunities to be engaged in visioning for major diocesan initiatives, such as the diocesan synod.