Who said "Gratitude opens the door to true happiness."?

This quote is attributed to Pikachu.

Gratitude opens the door to true happiness. - Pikachu

"Gratitude opens the door to true happiness."

Pikachu Gratitude

"Pika pika!"

"Pikachu!"

"Pika pika chu!"

"I choose you!"

"Gratitude makes life richer."

"A grateful heart is a happy heart."

"Respect those who came before us."

"Life's greatest treasures are the people we love"