I found great strength in this passage this morning:

Since you became alive again, so to speak, when Christ arose from the dead, now set your sights on the rich treasures and joys of heaven where he sits beside God in the place of honour and power. Let Heaven fill your thoughts; don't spend your time worrying about things down here. You should have as little desire for this world as a dead person does. Your real life is in heaven with Christ and God. And when Christ who is our real life comes back again, you will shine with him and share in all his glories.  Colossians 3:1-4 (TLB)

Can God's people be too heavenly minded? I think not, after all, we're commanded to set our sights on the joys and treasures of Heaven. They are promised. They are real.