I enjoy the fact that since i am in charge of so many pieces of machinery, equipment, systems, etc., it is hard to get bored as you would in other jobs. There is always something to be learned.
The work is challenging because you will never truly master every aspect of engineering. Especially with all the technology arising, once you have something down there is something else to learn.
There are many opportunities to advance, though sometimes you might have to move in to a different industry. Hospital to Hotels ..... Manufacturing to power plants .... Be honest with yourself and how much you know. Challenge yourself by continuing your education, and then take it to the next level.