I have several side projects which I do work on, but working on 25 hours for free on someone else's project is more likely to lead to future paid work than work

I have several side projects which I do work on, but working on 25 hours for free on someone else's project is more likely to lead to future paid work than working for 25 hours on my own projects. I also find it hard to justify working on my own projects when there's client work to be done.