This quote is so true. How you treat others is a direct reflection of how you feel about yourself. When you are happy with yourself, feel great about yourself, you know the importance of taking care of yourself, eat well, exercise, all the things that are so important to keep your health and your physical condition. Be kind to yourself. Take the time to enjoy life, and do the things that makes you happy.
And, when you feel good about yourself you automatically also will treat others with love and respect. As you do with yourself. When you meet someone being rude or treat you bad in some way, you can be sure that they are not feeling good about themselves. So, instead of taking the rudeness personally, try to see it as it is. A mirror reflection of how they feel themselves. And then it gets so much easier to not be affected of how someone else treats you. Let it pass. And instead, try to see if there is anything you can assist or help the other person with, how can you get the person you meet to realise and understand the importance of starting to treat yourself in the best way? And get into the same mood as you, instead of the other way around.
Wish you the best. Take Care. Namaste.