"Patience is a virtue" isn't more true in any place than the arena. Horses require an insane amount of patience, and it seems like it takes a lifetime to develop. Patience is the mark of a true, great horseman or horsewoman. As John Lyons once said, "There are only two emotions that belong in the saddle: one is a sense of humor, and the other is patience."
In our instant-gratification world, we sometimes forget that horses don't work like we do. If there aren't instant results, we get frustrated and look for a quick-fix solution- get a bigger bit, use spurs, pull harder, use a martingale, etc. How is it that modern trainers have forgotten the basics of good riding: taking time every day to help your horse understand what you are asking without force, brutality, or breaking the horse's spirit? Horses develop gradually; not only physiologically but mentally. Next time you get frustrated with your horse and lose your patience, take a step back and ask yourself if you aren't asking too much. Does your horse really understand what you are trying to ask? Have you taken the necessary steps and building blocks to ensure that is true? Is your horse in physical condition to perform what you want?
As riders, we should always remember to keep an equal partnership with our horse. I have seen many a rider who dominates their horse, and not in a respectful way. I believe that for our horse to reach his/her potential (as well as ourselves), we must have patience and complete understanding of the horse. Only then will our horse give us their best self, which should always be the goal in riding.