This scripture does not say we should not prepare for the future.
The center reference column of the National Bible shows that
"thought” could better be rendered “anxious thought”
according to the Greek. Christ was telling His followers not to
worry about the future. Maintaining a tranquil mind is
one of the seven laws of good health.
Christ was certainly not advocating that Christians make
no plans at all for the future. God knows we have need of
certain physical things (Matt. 6:31-32). He tells us to follow
the example of the ant who saves and plans ahead for the future (Prov.
6:6-8) and even specifically states in Tim. 5:8 and Prov.
13:22 that a man who does not provide for his family is derelict.
The point is we must not be presumptuous in making plans for
the future. James said, “Go to now, you that say, today or
tomorrow we will go into such a city, and continue there a year,
and buy and sell, and get gain: Whereas YOU KNOW NOT what shall
be on the morrow..For that you ought to say, If the Lord will,
we shall live, and do this, or do that” (Jas. 4:13-15).
Jesus is saying that you should not waste time making elaborate, intricately detailed
plans that you may never use. Keep your life simple and concentrate on the
basics. It’s a matter of emphasis. “Seek ye first the KINGDOM OF GOD and
his righteousness, and all these things (material possessions and physical
needs) shall be added unto you” (Matt. 6:33).