Excitement is a fleeting moment, not a steady state
Most work is pretty mundane. Even work on meaningful things. The most profound stuff is built one mostly boring brick at a time. Even the most creative ideas, the best art, the breakthroughs have to be assembled, and assembly isn’t typically what fires people up.
You don’t get to the exhilarating end without going through the mundane middle. And the beginning and end are the shortest parts — the middle is most of it.