I have seen that happen to myself. The motivation, the desire to pick yourself up and get to work drops.
The largest factor IMO is the people you work with ie Your boss, your teammates etc. This can make it or break it. Everything else comes and goes in time slices. I do not expect work to be interesting all the time but with great co-workers I at least expect an interesting hallway conversation or the spark to a new idea.
For me it was the Sr/Jr Engineer thing that killed my desire. I found that somehow my age/years of work experience came in the way by a highly regimented old world overlord. I figured it was an unhealthy environment that cared 2 hoots about what was happening in the world outside. Most of them had come from a school that thought sticking faster CPU more memory and larger disks was innovation while it was just evolution. Packed my bags and hopefully will never miss a thing :)
Good luck !