I've learned that things change, people change, and it doesn't mean you forget the past or try to cover it up. It simply means that you move on and treasure the memories. Letting go doesn't mean giving up... it means accepting that some things weren't meant to be.

Happiness needs sadness.
Success needs failure.
Benevolence needs evil.
Love needs hatred.
Victory needs defeat.
Pleasure needs pain.

You must experience and accept the extremes. Because if the contrast is lost, you lose appreciation; and when you lose appreciation, you lose the value of everything.

Remember the past, plan for the future, but live for today, because yesterday is gone and tomorrow may never come.