A "set" mind, not a wandering mind or a confused mind, is required for the day in which we live. We need a mind set on heavenly things. "Things" constitute a major part of life, and can affect us for good or ill. However, the Lord Jesus said, "A man's life consisteth not in the abundance of the things which he possesseth."
Since the believer's Father, Savior, name, reward, inheritance, and best interests are in heaven, it should be quite natural to set his mind on heavenly things.
This will not make him impractical. Paul was as heavenly minded while making tents as when preaching or writing his epistles. He could write about food, raiment, shelter and books, as well as about the unsearchable riches of Christ. The inclination and purpose of the Christian's life should be heavenly.