After the first round of the 2012–13 World Cup, Greis announced his retirement on 5 December 2012 citing a lack of motivation, making the 20 km in Östersund on 28 November his last competition as he had dropped the sprint and pursuit. After retiring, Greis studied International Management at Ansbach University of Applied Sciences. He also worked as a pundit for Eurosport. Subsequently in 2016 he was appointed as head coach at the national biathlon training centre for east Switzerland at Lenzerheide, where he coached youth biathletes. After two years in this post, in April 2018 he was announced as head coach of the United States men's biathlon team. After one season in this role, in May 2019 he was named as head coach for the Polish women's biathlon team.