Agdestein's career was interrupted in the mid-1990s by a knee injury, which he sustained while playing soccer. He was a professional footballer, and played for the Norway national team before his injury. By dual-artistry terms, he was a national champion in two sports at the same time, a unique accomplishment.
Presently, Agdestein is an active chess player and a high school teacher at the Norwegian School of Elite Sports. He also trained Magnus Carlsen, the World Chess Champion. He has written several books, one of which is on Carlsen.
Apart from his sporting career, Agdestein has also participated in the Norwegian version of "Dancing with the Stars," where he finished second.
He has made considerable contributions to the chess world during his ongoing career, leaving a lasting legacy. His coaching efforts, in particular, contributed significantly to Norway's emerging chess scene.