"Pain in life is inevitable but suffering is not. Pain is what the world does to you, suffering is what you do to yourself [by the way you think about the 'pain' you receive]. Pain is inevitable, suffering is optional. [You can always be grateful that the pain is not worse in quality, quantity, frequency, duration, etc]"

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Antisthenes used to say that envious people were devoured by their own disposition, just as iron is by rust. Envy of others comes from comparing what they have with what the envious person has, rather than the envious person realising they have more than what they could have and certainly more than some others and being grateful. It is really just an inability to get a correct perspective on their lives.

— Diogenes