Let someone else be first, top, best.
In other words let someone be more important than you today. Make it a point to let think of others better than yourself.
Here are some example in case you are stuck..
Let someone go ahead of you in line
High five a mom who is trying her best to parent her kids
Compliment the cashier at the grocery store on how quickly she gets the line down
Let the other car have the parking spot right next to the door
Encourage someone in your class at school