I've definitely noticed the same in my career. Its easy to get caught up in the day-to-day and forget some of the reasons you got started doing all this in the first place (in my case, because its fun and I'm passionate about software/hardware).

On a whim, I decided to invest time in writing down one idea per week of anything fun I could hack on. It doesn't really matter whether or not I go through with it, I keep the stakes low: just write an idea down. That way it forces me to think about things I could build for myself or others/friends/family without much cognitive investment.

The end result has not only had a nonzero impact on my motivation to start new projects, it has impacted my ability to actually follow through. And I've noticed the practice has made the ideation loop happen more frequently than once per week over time.