The idea of mounted games dates back to Britain in 1956, when Prince Phillip saw the need for a team competition for pony club riders who didn't necessarily have "show ponies".
He envisaged a series of games on horseback for teams of four riders - races that would be exciting for the spectator and rider alike and encourage outstanding horsemanship, skills and balance.
There are now about 40 games that can be included in competitions and test riders' skills, including dismounting and mounting while the horse is moving, handing equipment to the next rider at speed, picking up an item and placing it in a container, bending around poles, using a lance to hit something on the ground or using a sword to spear a ring on a pole.
Not only are the riders having fun, the horses are as well, Olivia says. "The ponies learn the games too. They get really excited, they watch the start flags and they even know when to slow down so you can pick something up or put it down."
Olivia discovered the sport when she went along to watch a friend training. Now she's hooked and it's a sport she can compete in to veteran level.
"You don't need special riding gear or clothing, and everyone is really friendly. You can compete as an individual or part of a team, and we all support each other."
During the world championships the New Zealand riders will be on borrowed ponies, an added challenge for the team.
"We won't know what pony we are riding until we get there," Olivia said. "It's just an additional skill we have to have, getting a good performance out of an unknown horse."
It is one of the things Olivia will be practising over the winter months.
"I will be working on my fitness and my skills, riding as many different ponies as I can, and doing a large amount of fundraising to get over there."