"Don't judge people - it makes you unhappy." - been judgemental is not a good thing, and additionally, very often I am wrong. But I never reflected that it actually also made me unhappy - this was simple advice for stopping me from making an opinion without the full context. And a full context is something that we rarely have in our hands.

Source: Ali Abdaal (sorry I can't remember which video)

"Don't do to yourself what you would not do to others" - it is the opposite of the normal saying and it is likely an even more important one. It reminds me of the airplane oxygen mask video saying to put it on yourself first then do it on others. Love yourself first then you will be able to love others even more. Definitely take care of yourself, you are the best person for your own happiness.

Source: Start Here with Mel Robbins (in the second episode)