When you love someone who doesn't love you, it's like you're taking a gamble, even if you don't know if you'll win or lose, even if you don't know the outcome, you still take a gamble, don't give up, do your best, you love that person even if you sacrifice your happiness, just make her/him happy with the person he/she loves.

You can love someone else, so don't waste your time on someone who doesn't care.

When someone knocks on your heart, don't hold back, but give it a chance,

I would rather focus my attention on the person who knocks on my heart than the person I dream of who has hurt me several times.
-by kane