I've struggled with keeping this kind of motivation for years. My way out involved getting an interesting job and finding a topic, which is somehow related to t

I've struggled with keeping this kind of motivation for years. My way out involved getting an interesting job and finding a topic, which is somehow related to the work (so that your reason doesn't fight) yet not directly aimed at a practical outcome in your work (to keep the enjoyment). For me, personally, the hobby part became SAT solving. It's related to software verification and theorem proving and I feel like learning something useful - even for my family through better career prospects (responsibility box ticked). And I still get the bit-fiddling just as when hacking old microprocessors.