The habits are the most powerful thing in the game of self improvement. When it comes to changing habits it’s logical to do so in the beginning of the game, in order to benefit most out of it.
But we, as creatures of comfort, are rarely trying to change our habits, because they define us in a way, and going against that definition we already set is usually very hard. Usually very hard, remember that.
Having a habit of any kind means that we are used to do things a certain way, thus changing the habit means changing the way we operate. That alone is the reason why people dread changing habits.