Kastenman took up horse riding at the age of 17, when he enlisted in the
Life Regiment of Horse in
Stockholm. He attended the
Army Riding School from 1946 to 1947 and in 1949 he transferred from K 1 in Stockholm to the
Life Regiment Hussars (K 3) in
Skövde. In 1950 he passed
realexamen (graduation from
Realskola) and in 1951 he attended the
Swedish Army Non-Commissioned Officer School. In 1969, his family moved to
Borgunda, where he built a championship eventing course. During the 1970s and 1980s, he was the national coach for juniors, young riders and pony riders, and also coach of the Norwegian and the Finnish national teams. At one time, he coached five different teams. ==Personal life==