There is a Hasidic teaching that says you should carry two slips of paper with you in your pockets at all times.
On one slip of paper, write the words "For my sake the world was created"
On the second slip of paper, write the words "I am but dust and ashes."
Put one slip in a left-hand pocket and the other in a right-hand pocket. These messages are now available to you whenever you need them. Which message you should reach for at any given time will depend on what your needs are at that particular moment.
If you are feeling arrogant and overly full of yourself, reach for the slip that says, "I am but dust and ashes." This will remind you of your mortality, which will help you keep your ego in check.
If at another moment, you feel discouraged and overly self-critical, read the slip that says "For my sake the world was created." This will remind you that life is full of wonders, that you have an important role to play, and that a transcendent power, or the Universe, loves you.
Carrying these two slips helps you stay in balance. From day to day and from moment to moment our thoughts, feelings, and moods can shift. Low self-esteem and arrogance can sometimes be two sides of the same coin, both stemming from insecurity, and it's common for people to flip from one to another. No single antidote applies to all situations. The beauty of the two-slips method is that you will always have the antidote you need.
Try it for yourself. Write out the two sayings, using either the traditional wording or phrases that are personally meaningful to you. Be mindful of your thoughts, and when you catch yourself thinking that you are better or worse than other people, reach for the appropriate slip that will bring you back to center and remind you we are all the same.