Jack started his jumping career when he was 10 years old. At that time, his biggest motivation was his grandpa Jan Mooy, who gave Jack his first pony. He learned a lot of him and was always supported by him, his mother (Ageet Ansems-Mooy) and father (Jaco Ansems). He had a successful period while riding ponies and as Junior and Young Rider, he rode different European Championships, won several medals with the team and as individual.
In 2005 he started to work for VDL and gained experience at large competitions all over the world. He had a great time at VDL but after these years of experience, he decided to focus himself on his own stable ‘Stal Tandhof’.