Singleness of purpose; that's what I hear in this passage. In life or in death, there is only one purpose, i.e., to live for the glory of God. That might mean to live directly in his presence or to enhance the image of the glory of God in others. Yet it is all focused on the glory of God.
"If I am to go on living in the body, this will mean . . ." For most of us it means to go on working and seeking entertainment through some form of self-gratification. It means acting just like everyone else who has no clue regarding what life is really about. It should mean that thousands of us make decisions that look really strange to those around us. It should mean that we distinguish ourselves from everyone else by service to them. It should mean more time to be more different than the rest of society.
One of the great driving motivators in this has to be that death is not death but rather a transition to the presence of God. On the Mt of Transfiguration, Moses and Elijah talked with Jesus about his "departure". In John 13, Jesus knew he was about "to leave". Here Paul talks of departing and even qualifies living as "in the body" since a follower of Christ never really dies.
So why not be different? Why not live as one who is in on the big secret (the mystery as Paul calls it) while others don't know what the game of life is about. Life is never-ending and should forever have the same focus, i.e., to live for the glory of God.