Sorry for the slow reply...and because I don't have any good advice to offer. To be honest, I don't have an issue finding motivation, I simply enjoy making games. Even if I never released anything publically, I think I'd still spend my free time creating them anyway. Part of it is definitely the subject matter too, since I make the kind of games that I want to play. I don't think I'd have fun if I was just making a first person zombie shooter or something like that.