"...but lay up for yourselves treasures in heaven, where neither moth nor rust destroys and where thieves do not break in and steal. For where your treasure is, there your heart will be also." (Matthew 6:20-21 ESV)
"But our citizenship is in heaven, and from it we await a Savior, the Lord Jesus Christ..." (Philippians 3:20 ESV)
Søren Kierkegaard, the Danish philosopher, wrote about anxiety and despair, and about faith and singleness of mind and will.
He said, "To despair is to lose the eternal." Here is one of his written prayers...
"Father in heaven! Draw our hearts to you so that our longing may be where our treasure is supposed to be. Turn our minds and our thoughts to where our citizenship is – in your kingdom, so that when you finally call us away from here our leave-taking may not be a painful separation but a joyful union with you. We do not know the time and the place, perhaps a long road still lies before us, and when strength is taken away from us, when exhaustion fogs our eyes so that we peer out as into a dark night, and restless desires stir within us, wild, impatient longings, and the heart groans in fearful anticipation of what is coming, oh Lord God, fix in our hearts the conviction that also while we are living, we belong to you."
~ Søren Kierkegaard, Provocations, 58