3 Nephi 13

We learn a great deal more about the Savior's intructions in the New Testament, as the Savior continues His teachings in the Americas for -

"...when Jesus had spoken these words he looked upon the twelve whom he had chosen, and said unto them: Remember the words which I have spoken. For behold, ye are they whom I have chosen to minister unto this people...."  (Book of Mormon 3 Nephi 13:25)

It is then to His twelve priesthood leaders or apostles that He teaches -

"...Therefore I say unto you, take no thought for your life, what ye shall eat, or what ye shall drink; nor yet for your body, what ye shall put on. Is not the life more than meat, and the body than raiment?"  (Book of Mormon  3 Nephi 13:25)

It becomes obvious that these instructions were not necessarily given to all disciples or saints.  This is when he uses these analogies -

"Behold the fowls of the air, for they sow not, neither do they reap nor gather into barns; yet your heavenly Father feedeth them. Are ye not much better than they?
27 Which of you by taking thought can add one cubit unto his stature?
28 And why take ye thought for raiment? Consider the lilies of the field how they grow; they toil not, neither do they spin;
29 And yet I say unto you, that even Solomon, in all his glory, was not arrayed like one of these.
30 Wherefore, if God so clothe the grass of the field, which today is, and tomorrow is cast into the oven, even so will he clothe you, if ye are not of little faith.
31 Therefore take no thought, saying, What shall we eat? or, What shall we drink? or, Wherewithal shall we be clothed?
32 For your heavenly Father knoweth that ye have need of all these things."  (Book of Mormon   3 Nephi 13:26 - 32)

In that we have been taught to apply the scriptures unto ourselves, this is where we need to contemplate if any of these teachings apply to us.  Obviously, all saints can't go through like not planning, preparation, or taking no such thought on the matter.  Yet at the same time, on the other side of the pendulum, there are His twelve apostles that he has counseled exactly to do that. 

My thoughts are that we all are somewhere in between depending upon the stage of our life and upon the callings we receive.  It is a balancing act where we do the best we can considering our spouse, family, and our desire to serve God.  We must always consider that which is good, better, or best remembering that the Holy Ghost -

"...will show unto you all things what ye should do."  (Book of Mormon  2 Nephi 32:5)

With that it then makes sense -

"...But seek ye first the kingdom of God and his righteousness, and all these things shall be added unto you.
34 Take therefore no thought for the morrow, for the morrow shall take thought for the things of itself. Sufficient is the day unto the evil thereof."  (Book of Mormon  3 Nephi 13:33 - 34)