What does Matthew 6:28 mean?

Matthew 6:28 KJV
And why take ye thought for raiment? Consider the lilies of the field, how they grow; they toil not, neither do they spin:

Matthew 6:28 MKJV
And why are you anxious about clothing? Consider the lilies of the field, how they grow. They do not toil, nor do they spin,

Matthew 6:28 NKJV
“So why do you worry about clothing? Consider the lilies of the field, how they grow: they neither toil nor spin;

Matthew 6:28 KJV 2000
And why take you thought for clothing? Consider the lilies of the field, how they grow; they toil not, neither do they spin:

Interlinear KJV

And /kai/ why /tis/ take ye thought /merimnao/ for /peri/ raiment /enduma/? Consider /katamanthano/ the lilies /krinon/ of the field, /agros/ how /pos/ they grow; /auxano/ they toil /kopiao/ not, /ou/ neither /oude/ do they spin: /netho/

Adam Clarke’s Commentary

Verse 28.   And why take ye thought for raiment? — Or, why are ye anxiously careful about raiment?  The fourth reason against such inquietudes is the example of inanimate creatures: The herbs and flowers of the field have their being, nourishment, exquisite flavours, and beautiful hues from God himself.  They are not only without anxious care, but also without care or thought of every kind.  Your being, its excellence and usefulness, do not depend on your anxious concern: they spring as truly from the beneficence and continual superintendence of God, as the flowers of the field do; and were you brought into such a situation, as to be as utterly incapable of contributing to your own preservation and support as the lilies of the field are to theirs, your heavenly Father could augment your substance, and preserve your being, when for his glory and your own advantage.  

Consider — Diligently consider this, katamayete, lay it earnestly to heart, and let your confidence be unshaken in the God of infinite bounty and love.