Magical medicine. Your son, your heir, has been cursed by a terrible magical disease. No one in your kingdom could find a cure. You sent out adventurers to find a cure, but none have them have found anything. You finally turned to that annoying prophet who claims to speak for the true God. That man Teman had the nerve to say that only you would be able to find the cure, and only if you humbled yourself and went in secret! It sounds absurd, but nothing else has worked and somehow this man is always right so you have to try it.
Adventure! They cannot expect you to stay cooped up in that stale old castle. You will return in a bit to catch up on work, but for now the horizon calls to you and you are off to see it.
An Army. After your land was invaded you need an army, but if you reveal yourself too seen your enemies will try to finish the job.
A wife. You are sick with all the ladies parading around you trying to impress you. You have entrusted your kingdom to your closest advisor and gone seeking a woman who will love you for who you are not the title you bear.
You are the rightful heir. You were raised to the throne, but to many doubt you have what it takes to unite such a fragmented country. You have but one option, you must seek out the Hall of Testing. Somewhere out there is a place where your great ancestor left his great legacy. It is rumored to be protected by magic so strong that no one can force their way in, and it will only open to one of noble blood and noble heart. If you can find it and prove yourself worthy then you should be able to return to your country with your ancestor's great power and they will have to stop their infighting and begin to work together.