What is a piece of advice you received which shook your world and set the foundation on changing yourself?

"Well you need to stop giving a shit about the rest of the world and start looking after yourself and your own people. Do you think your sensitivity, righteousness and idealistic views on how things are supposed to be will get you far? All those will ruin you, you keep ruining yourself and people will continuously take advantage of that, mark my words."

Worst part is that piece of advice has affected me deeply. It still hurts when I recall it.
What is a piece of advice you received which shook your world and set the foundation on changing yourself?
What is a piece of advice you received which shook your world and set the foundation on changing yourself?
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