Sometimes the best way of challenging yourself and your skills in horsemanship is to make the goal of some of your rides simple, pure fun. Whip tossing, riding bareback, going for a hack and opening and closing all your gates along the way are great ways to enjoy the summer. Going for a really good gallop is an amazing way of reminding yourself of the sheer power of your horse and to feel the aliveness of your heart pumping. If you have a friend who would be willing to help you out, get on the longe line and do some vaulting work or close your eyes while you do ordinary gait work.
Be safe and then push the limits a little. I hope you have a good time making new discoveries!