The novelty of the job keeps your energy high. You are happy because you are so productive, and you're more productive because you are so happy. Then the second stage, reality, sets in. You still enjoy the work you do, but you begin to notice some of the irritants and difficulties. It bothers you that all the phones are ringing when you walk in the door.
Deadlines seem endless and impossible.
It becomes harder to arrive early or stay late. The novelty starts to wear off. And, like love, your job has a third stage too disillusion. The pendulum swings past reality, and you find yourself focusing on the negative things. Maybe Company Z would let me come in a little later in the mornings or go home earlier at night.