That's an interesting pick, as it touches on exactly the issue I ran into in my last startup: getting customers, getting traction but finding myself unmotivated by the problem being solved. Not seeing myself doing that for another year, let alone the rest of my life.
While I was working on my previous startup I actually started asking myself how other founders kept themselves motivated while dealing for really long periods of time with the same industry and similar set of problems (even if they are approached with multiple hats, like engineering, marketing, finance, etc.)
Thanks!