This trophy can be earned as soon as you start the game by riding Agro right out front of the Shrine of Worship.
Stand next to Agro and press
to pet her. Then mount her and pet her again by pressing
.
Press
+
while stopped to do a quick start (Agro will rear up on her hind legs, then sprint forward).
While galloping, press
+
and Agro will stop quickly.
While galloping, press
+
to initiate a quick stop and then quickly press
+
again and Agro should reverse directions.
While galloping, hold
+
and Wander should stand up on Agro.
While galloping, hold
+
and press
. Wander should hang off to the left side of Agro.
While galloping, hold
+
and press
. Wander should hang off to the right side of Agro.
While galloping, press
and Wander will jump off of Agro.
Ride Agro in a gallop towards a small cliff or rocky area and she will jump off, resulting in a jumping animation.
After performing all of these actions, the trophy should pop. I had to repeat a few to get it to work.