OK I'm going to be a bit controversial here.
I think that, having decided that you're passionate about a project that you need to force yourself to start. How many personal projects hit the buffers and never get anywhere? Most of them. Of those that do get started, how many never finish? Almost all of them.
Ultimately it's human nature to be lazy, to not want to do even more work in your spare time, etc. but what it comes down to is getting the momentum going. Once you have the ball rolling you'll find you have far more time and energy for it than you ever realised.
I'm not saying you should be unhealthy with it, or force yourself to do something you don't wanna do, rather you have to force yourself to get started and let momentum take care of the rest. Once you're doing it, you should be enjoying it. It's like the spark plugs in an engine. Occasionally you'll need to force yourself for short bursts, there are always boring and vexing aspects of any software project, but once you're done you won't regret it.
I think treating these projects like they're equivalent to watching TV or other leisure activities is the problem. You should consider them equivalent to training for a marathon - loads of work, sometimes a death march but the end achievement is so worthwhile you would happily do it all again 100 fold.
When it comes to the end of the project, shipping is also tough as hell. I wrote a blog post about shipping a personal project here, quoting Michael Abrash, a legendary coder who worked on Doom and Quake, who achieved quite stupendous results especially in the field of optimisation. Allow me to quite Michael:-
My friend David Stafford, co-founder
of the game company Cinematronics,
says that shipping software is an
unnatural act, and he’s right. Most
of the fun stuff in a software project
happens early on, when anything’s
possible and there’s a ton of new code
to write. By the end of a project,
the design is carved in stone, and
most of the work involves fixing bugs,
or trying to figure out how to
shoehorn in yet another feature that
was never planned for in the original
design. All that is a lot less fun
than starting a project, and often
very hard work–but it has to be done
before the project can ship. As a
former manager of mine liked to say,
“After you finish the first 90% of a
project, you have to finish the other
90%.” It’s that second 90% that’s the
key to success.