“Those who are happiest are those who do the most for others.”
– Booker T. Washington
Having a bad day? Go help someone else.
Having a good day? Share your joy with others.
If things are not going great in your world, there is always many people who have it worse, who would willingly trade places with you. Do something from what you have to lighten their burden in some way, even if it is just a smile or a kind word or picking up something for someone else. It will make them happier and by extension lighten your mood.
If things are going great in your world, share the joy and the love. Spread your smile to those who may be lacking. Help another in some way. Do something for others because joy shared is joy multiplied.
No matter your current situation, you will be happier and the world better if you take a moment to help others.