How do you know if what you have is worth fighting for?

personality is more important than looks right?well i believe so anyway, even though good looks are also an added bonus....however what do u do if your in a relationship where your partner is the nicest person you cound ever meet and has all the lovliest qualities but you are not physically attracted to them and sometimes you let that get in your way or you let that doubt your true feelings for the person! are all the other things that you love about the person more important and are they enough to make you fight to let your relationship prosper and learn to live and accept the things that are not as important or should you just reconsider the whole thing?