You don't need to point out someone's dark spots on her/his face. You don't have to tell them they're fat or short in height. Trust me they already know. Just be kind and let it go.
Once you realize that anything can happen; sickness, death, lose your job... Literally, anything in the blink of an eye, you become very humble. Tables turn and that's how crazy life can get.
Always stay humble, and be grateful.
They'll never know your value until you become a memory. Before sacrificing yourself for ungrateful people, don't forget to love yourself first and take good care of yourself.