Jesus demonstrated it first. He sat on the throne of heaven and gave it all up to be born a baby in a feeding trough. He ruled the universe, only to then take a job as a carpenter. He invented and sustained life itself, only to let his invention take life from his own body. But he did it all because he loved his father who sent him and loved people like you.
To live second means you follow in this example. You put love of God above everything else. And you love others before yourself. You can say it is the golden rule, but really it is the Jesus rule. Jesus first love you so that you could have the power and the example to love others and Live Second.