Feelings are just carved in the heart. No matter how much our memory fails us at times in remembering things, we can never forget how we really felt at an exact moment with a certain person.

Treat people the way you want to be treated and be considerate.
Be thoughtful.
Be selfless.
You don't know if you had hurt someone and made yourself an enemy, or if you had comforted a heart and just made an admirer for life.