There is nothing better to make you appreciate what you have than to experience the opposite. I've heard it said that if everyone threw their problems into a pile to pick from, you would always choose your own back again after you saw the options.
I had that moment Friday when I rode a different horse in my morning training. Where Flame is light, sensitive, and hot-tempered, this horse is heavy, dense, and rather dull. Someone joked that he is a cross between a draft horse and a cow. It was an exhausting workout and I never could get him truly round and forward. But it was a good experience since I will now approach Flame with new appreciation and patience!