Sanne rode in her first showjumping competition at age seven. Her father (Leon Thijssen) is an international showjumper and she started competing on ponies, before changing to horses and starting her international competition career at age 15.
Her father Leon Thijssen has competed in showjumping at elite level and represented the Netherlands at the 2005 FEI European showjumping championships in San Patrignano, Italy. In May 2016, at age 17 Sanne became the youngest ever winner of the Eindhoven Derby competition - she rode the 15-year-old horse Ulena, a horse that her father had previously competed on.
She combines her high school studies along with riding horses at her family's Stal Thijssen in Baarlo, the Netherlands. "When I am not at a show, I go to school. Around 3 or 4pm I am back at home to ride seven or eight horses. My groom is there to help until 6pm and after that I do everything on my own. That is not stressful for me, it is fun. Even though it is tough sometimes."