Can't control my feelings

I just can't control my feelings. One moment up, one moment down. I really hope to one day find peace with myself.. Such a tough life, is it worth living? Every tear, is it worth crying? Every smile, how long does it last? You're the source of my happiness and my pain. When do we fight to hold on to happiness and when do we decide to let go of pain? Wish vs reality. Are we really suitable? What will the future hold?