In 1999, Upton moved with her family to Melbourne, Florida, where she was a student at Holy Trinity Episcopal Academy. As a young equestrian, she showed at the American Paint Horse Association (APHA) and competed at a national level. With her horse Roanie, she won three APHA Reserve World Championships – 13 and Under Western Riding, 13 and Under Horsemanship, and 14–18 Western Riding. She was named the 13 and Under Reserve All-Around Champion, giving her a total of four reserve championships (2nd place). In addition, Upton ended up third overall on the APHA youth Top Twenty. With a second horse, Colby, she won 14–18 Western Riding and was included in the top 5 in 14–18 Horsemanship and 14–18 Western Pleasure in 2009.