I think the last time I did one, I was 9.
I understand that some profs will make you endure this stupid thing when you are just beginning your training.
If this is the case you have two options
1. Position yourself in a horse stance wherever you go. In line at the grocery store, when taking a sobriety test, when picking up a girl at a bar, in the shower, at dinner, over the toilet to take a crap, at the movies, at work, on the bus, and so on. This ability to remain in the horse stance and endure any future tests of boredom will surely impress your instructor.
2. Find a new dojo
I honestly don't mean to make this sound like a flame my friend. My first Kenpo instructor made us stand in that stupid thing for hours. He'd stand on our knees and whack us a little, old school style. This was merely a test to see who would stick with it. After that, we began to learn things that had actual value.