1- Grateful hearts are happy hearts. Taking a moment to be grateful for your blessings makes you happy.
2- Gratitude keeps you humble. Usually humility is seen as a weakness. But humility is the antithesis of arrogance, and pride. Humility doesn't mean "poor." In fact, humility is what brings our lives and the lives of others into perspective. The richest man in the world could be humble and greater because of it, when he is grateful.
3- Gratitude is the key to effective prayers. Never forget that.