In other words, keep on keeping on. "A couple of hours" of focused work is actually fairly productive, more productive than most people get. It's like writing: do a little bit every day, pretty much no matter what, and it'll get done by accident.
However, it’s worth noting that you should expect to not want to do things sometimes. Often pushing past the first part is the key.
Set. Minimum amount to accomplish. Nothing ambitious but something you can easily do. (2 hours if you don’t have kids. 45 min if you do)
If you find yourself not wanting to do it week after week then you might consider changing your role. Partner with a CTO, raise money, write about it etc.
You don’t have to do what you love, but you should avoid what you hate.