|Oh, how I love you computer - debugging is sheer bliss...|
Just describing personal experience in terms of burning out - I think to a certain extent you can develop as much as what you've already made is somewhat fun already. It's kind of like a budget - if what you've already coded is a bit of fun, that gives you the drive to code more. The tactic is to then take that and code something else which is a bit fun. Which in turn gives you more 'budget'. Because if you go and code some monsterously huge code which is all support infrastructure and boring, you'll likely burn yourself right out/run out of budget.
Anyway, trying to do a massive project which is completely boring and even painful to look at until it's 100% complete, I think, is a recipe for burn out. Try and always make little things that'd be fun right now, even before the projects fully complete.