I must be grateful, right?..........

For eveything that I hav.. for everything that He gave. I must be grateful & thank to God so many times. I must be positive, not rumbling so often, not feel sad for everything that i lost. For that wasted time..... i must be happy right? Smiling, cheer up and singing all the way. That I must be...right?... So why? My heart keeps telling me there is something wrong... like my heart been tied up, tightly. Is there any "leaking"? From inside..... empty or frozen?..... i must.............. be happy...........right?