The truly prolific creative people I know do that work at non-traditional times if they have a full time job. Practicing music late at night, painting at 6am, etc. Even scheduling their creative work during low points in their work day.
I am also not good at this, so take this advice as an observation rather than a personal experience.
For me the first several hours of the day are my most productive/creative, so I carve out at least a couple of those for my personal projects. Lately that's meant getting up early (5:30-ish) and prioritizing my own work ahead of my employer's.
So we just have to make do with the 7.5 hours at work.
It did take a few years to become consistent though.
Small children require a large amount of energy to maintain. If you’re responsible for providing that energy then you’re gonna have less for projects.
Or outsource the work.