A sum up of how is like:
It's the same, either you are media or creative agency, shit just happens to you and it will keep coming. So just be hungry at all times.
On my first week as an assistant planner, the brief introduction from a very experience media owner was: Hey kid, welcome to the industry. It's no difference of where you are, be it agency, creative or media owner. The shit is same, it just comes with different serving.
So in first year, things are hard. It's like scaling a ladder with the bottom on fire. If you got a problem, hope that your boss knows how to solve it, learn from it and not make it another problem again. So if you survived year one, you should be pretty well armed with all the knowledge that will keep all the problems at bay.
So in year two, things are slightly easy, seeing that if you had hit enough brick walls in the first year, you should be smart enough not to hit any on the second year. Well, fuck you, that's what life say. So you are on this ladder, the end is burning; and when you look up, bricks are falling down around you. If you are just unlucky, the whole wall just came crushing down. It's really a leap of faith that you will need to take to see where you land to.
So in year three, given that if you manage to learn to fly or to land softly; things then will be very easy. Sometimes it just that you throw a brick down to see if the juniors are build up to it.
It's quite self explanatory, like this: