Messenger

Information are priceless and very hard to come by in the medieval time of trying to get birds to listen to you and go a certain direction while not being shot, or riding on dozens of horses to get somewhere and completely lose any feelings in your bottom area along with the hope of ever being able to create any offspring or even wanting to use your lower bits ever for any purpose at all whatsoever.
Being a messenger is a job that has many priviledges as well as dangers associated with it. Even if you decide to serve a lower lord or just get word around among villagers, you are seen with respect and not many people are willing to cross your path. Not just anyone can become a messenger and be expected to get paid for it however. While local children can only expect a couple of coins or a quick snack if they pass on some message to a villager next door, joining this profession requires much more skills than just walking and yelling at people.
For the most part, you need to be trustworthy and honest person, even if you don't plan on delivering secret messages. People who deliver documents across the land have a special insignia of their lord signifying that they have been chosen for this profession by a figure of authority and therefore can be trusted with any message people might want to entrust in them. Usually it is a decree or a ring or a special uniform or colours, but this heavily depends on the region and who employs said messenger.
Secondly, you need to be fast and nimble - on a horse and off of it. Running is often times a necessity, especially if you do decide to deliver some secret messages or venture into a territory that is less than friendly towards a civilisation of written word. Being able to read or write is discouraged, as no one wants the capable messengers to actually know what they are delivering.
Some people might get chosen to only deliver spoken messages but for that one has to prove that their memory is incorruptible not just by time but also torture. Those messengers fear nothing and will only serve their true purpose of protecting information at all costs.
In exchange for that a messenger can always expect to be fed, get a fresh horse and get a bed to rest in after a long travel. They also get to see places all over the kingdom and some, that a common peasant could only dream about.