Think about another situation concerning gratitude. Someone helped you to pass tests so you can go onto a very prestigious college. At the time you were so thankful. But over time, going to the school, getting involve in other life projects, your feeling of gratitude fades away. Why? Because you forget the details and the feelings as when they were fresh in your mind.
Take another situation. Setting New Year's resolutions. You visit an old roomate from 15 years ago. They didn't take care of themselves and gained 100 pounds. They look very bad and overweight. You promise yourself you will take care of yourself, and lose 30 pounds. You are very motivated. But in a short time, you forget the effect of seeing your old friend. You forget the energy behind seeing your overweight friend. So you don't really pay attention to yourself and start gaining weight yourself. Why? --> Do Not Forget.
This applies to many different type of lessons. Physical events, Mental events, and spiritual events.
Do you remember?
Wisdom by Great Grandmaster Tae Yun Kim