"To be grateful is to recognize the Love of God in everything He has given us -- and He has given us everything.  Every breath we draw is a gift of His love, every moment of existence is a grace, for it brings with it immense graces from Him.  Gratitude therefore takes nothing for granted, is never unresponsive, is constantly awakening to new wonder and to praise of the goodness of God.  For the grateful person knows that God is good, not by hearsay but by experience.  And that is what makes all the difference." (From "Thoughts In Solitude" by Thomas Merton)

A grateful person, I would say, is a happy person, even in the midst of difficulties. So often we place our happiness in things, not in God. When we begin to see our life through the lens of gratitude, then we will realize how blessed we really are, maybe not in material things, but in the things that pertain to God. Be attentive to how often during the day do we express gratitude to God for his blessings, in comparison to how often we petition God. What would happen if we bookend our petitions with gratitude?