Nothing revelatory here. This practice of reciprocity dates way back to ancient Chinese philosophy. And seemingly every religion and philosophy throughout history teaches some rendition of this core principle, also known as the golden rule: treat others kindly; the way you would want to be treated. Simple enough.
Everyone you meet is struggling with something you know nothing about; so be kind, always. And, LOVE. Love your family. Love your friends. Let them know it through your actions.
Don't go to bed angry; things get worse when you let issues fester. Address and resolve right away - a good rule of thumb is 24-hr rule: if you're having an issue, you have 24-hrs to address and resolve it otherwise put it behind you and move on.