There was no reason for any of it to happen.
As the days of peace in the world grew longer and longer, there was little conflict to mention. Now and then, a fire bender would get out of hand, setting fire to a house. Other times, an earth bender farmer would get overzealous, shaping the land for his own sake, never for the sake of others. The accidental flood brought on by the occasional water bender would devastate a port town. The air nomads, those who would have been most responsible with their bending, would have been the easiest to handle. But in these times of peace, there was no great imbalance for the avatar to handle.
Which is why, of course, Li didn't see why he had to train that day.
"What does it matter?" he shouted, pacing around the training yard. "There is no war! There is no imbalance! There is… There is only peace! Why was I born in a time like this with responsibilities like these?"
The target dummies nearby offered no answer, of course, standing in their endless vigil, their loosely stitched faces appearing as despairing as always. Li stopped pacing, sighing as he bowed his head. There must be some reason. There always is. He thought back to history, the history of the avatars. Keoshi… Roku… I've heard about them. Even in times before the great war, they still had troubles to right. But… More recent history bubbled to the front of his mind. …But there isn't even a little bit of instability. People even have the sense to live a safe distance from volcanoes. There's literally nothing I can do. The young fire nation man looked up at the training dummy in front of him.
"…Why was I born?"