Welcome to Shin Buddhism!
There are many branches to the tree of Buddhism. Our temple belongs to a branch of Mahayana Buddhism known as Jodo-Shinshu. It is a single-practice school where gratitude is practiced because we do not have to conduct the arduous practices famed to bring about happiness (meditation, seclusion, asceticism, etc.)
The Path to Gratitude
"We don’t practice to achieve anything—not enlightenment, good karma, a favorable rebirth, or material rewards. We practice simply to give thanks for what we have received." This is a quote from an excellent summary article of Jodo-shinshu Buddhism by Jeff Wilson
Shin Buddhist links
We should look on the Nembutsu as an expression of gratitude for the Buddha's great benevolence and compassion. We should say it all our lives, thinking, "If it were not for Amida's compassionate Vow, how could such a wretched evildoer as myself ever hope to be liberated from samsara?"
Yuien bo's Tannisho translated in Alfred Bloom's Strategies for Modern Living: A Commentary with the Text of the Tannisho (pg 15, 1992)