This happens to everybody who achieves an initial "success":
- A band or artist that puts out a great first album or single that is well received and then struggles to write any more hits. These guys are called "one hit wonders" - what a horrible name for somebody who achieved success even if it was once!
- An entrepreneur who launches a successful first business, sells out for millions, and struggles to come up with an idea for a second business let alone execute and replicate the success of the first.
- The writer that has a successful first book but can't come up with a story line for a second.
I'd estimate 99% of people never have one "success", let alone repeatedly create successful things - it seems unfair your brain beat you up for not having replicated your first success. Glad to hear it's getting better.
However I agree with the idea that being motivated by the process of creation is more robust than being totally goal-oriented, especially when chance of achieving a goal is low and it may take many unsuccessful attempts before producing a hit.
According to studies done on musical students (for what these studies are worth), the ones who practiced in "flow" progressed much slower than those who constantly and deliberately pushed themselves far outside their comfort zone.
(Not advocating that, that's just how I would understand the concept)
New projects weren't having as much an impact and making me feel good, so I sat around reading books.
A turning point came when I read two: Flow by Mihaly Csikszentmihalyi and On Writing by Stephen King. The first teaches we get optimal experience out of what we spend our attention on. It really got me psyched about chasing that feeling of being in the zone with my work. On Writing did that too. I saw another HN poster refer to King's "blue collar work ethic" -- totally true. He works hard because he loves to.
I recently started working again for pleasure, less encumbered by insecurities. I'm still working on it, still practicing. I created an open source framework for Amazon Echo development, and it's starting to get some traction. I think I was able to produce the work to get the traction because I've had a clearer mind.