Having test readers have really helped keep motivation up. Many of them are just acquaintances, other aspiring writers and some are friends. Luckily, I know they are honest people and most likely not afraid to hurt my feelings, so their compliments mean a whole lot to me.
If you’re writing your first book, I suggest getting several test readers of different backgrounds and lifestyles to give you their thoughts. (Not editing or grammatical corrections because you can always go back in for that when it comes to polishing your final pages) More feedback regarding your story and characters.