"Do not worry then, saying, 'What will we eat?' or 'What will we drink?' or 'What will we wear for clothing?' "For the Gentiles eagerly seek all these things; for your heavenly Father knows that you need all these things. "But seek first His kingdom and His righteousness, and all these things will be added to you. (Matthew 6:31-33 NASB)
Jesus gives the purpose of His teachings on worry at this point. In the previous two posts you can see the reasons which we should not worry, and the reason we should not worry is because we can trust in the character of God our master. We know we are valued above birds of the air, and grass of the field, and most importantly that we have a good master who is not going to let His servants go uncared for. What then is our response? Our response is the reason Jesus has opened our eyes to not worry, and that is that we would "...seek first His kingdom and His righteousness, and all these things will be added to you." Because we do not have to worry about our clothes or our food we only have one thing to concern ourselves with... seeking Him first.
It is also incredibly important that we notice that we are seeking HIS kingdom, and HIS righteousness. Missing this critical point will leave you in a greater state of worry than you started with. If you were seeking to build his kingdom, you would be seeking to do a work that is impossible to do, and if you are seeking your own righteousness or to become righteous you will also leave yourself in utter disappointment. However the goal of the Christian life is singular, and that is to know God. Really, that is the only goal. That is what salvation is, to know Him, the one true God. All of our actions and intents must center around that one singular focus, the simple seeking of His kingdom and His righteousness... seek Him... seek Him... seek Him.
I have been in e-mail contact with a younger friend of mine, a dear friend, and he has mentioned his struggle in prayer, and his unworthiness before the Lord. Yet hearing him allows me to sit back with confidence knowing that his struggle will not be in vain, and that great blessing will come from it. Why? He has begun to seek the Lord, to seek His kingdom, and His righteousness, that's why. Now, it will not result in a best life now, but in a struggle against the flesh, and a desire at times to quit, and toil in prayer, and so on. At the same time fountains of blessing and knowledge of God will spring forth and he will be so grateful for the struggle.
Do not worry about the things the pagans worry about... what to eat and what to wear, seek the kingdom and His righteousness, clothes and food will become afterthoughts to you.