I do not know if japanese will keep you motivated, but next month i will finish the fifth year of the japanese course and i can tell that i feel very happy for everything i learned. I think will be great for you. Personally, the way i use to keep me motivated is think in my age, lol. I want to do everything i can while i am kind of young, i do not want to look back when i reach 50 years and think, "oh shit, my life is almost over, there a lot of things i still need to do".
My personal thought: makes me angry the shit topic at neogaf where they say that Nintendo must do a Sonic game. If this happen someday, i will not buy. I got very angry seeing them bash Sonic Team. I wanted to see Sonic Team make a fantastic new ip like Nights and shut up the mouths of this guys.