Casting all your care upon Him(Jesus),for He cares for you.

Casting all your care upon Jesus - First Peter 5:7 says these comforting verses. Comforting because it gives us the guidance as to where we will find a person to whom we can share all our griefs ans sorrows, where we could find peace and relief.

The hymn "What a Friend we have in Jesus" reminds us of his unconditional love as making us as friends and helps us in our griefs.

1

What a Friend we have in Jesus,
  All our sins and griefs to bear!
What a privilege to carry
  Everything to God in prayer!
O what peace we often forfeit,
  O what needless pain we bear,
All because we do not carry
  Everything to God in prayer!

2

Have we trials and temptations?
  Is there trouble anywhere?
We should never be discouraged,
  Take it to the Lord in prayer.
Can we find a friend so faithful
  Who will all our sorrows share?
Jesus knows our every weakness,
  Take it to the Lord in prayer.

3

Are we weak and heavy-laden,
  Cumbered with a load of care?
Precious Savior, still our refuge—
  Take it to the Lord in prayer;
Do thy friends despise, forsake thee?
  Take it to the Lord in prayer;
In His arms He’ll take and shield thee,
  Thou wilt find a solace there.

1 Peter 5:7New King James Version (NKJV)

7 casting all your care upon Him, for He cares for you.

Casting ALL your care: Not only few... its all... all the cares... Jesus when teaching about the parable of the sower, he said one of the seed would be that which grows to a certain point and then perishes because of the thrones and the bushes that brings down the growth of the seed, he was saying that the world and all its care will bring down the faith of these people who believe in God but because of the cares of the life they may go astray in unbelieving and end up being ignorant for the word of God.

Luke 8:14 NIV 

The seed that fell among thorns stands for those who hear, but as they go on their way they are choked by life's worries, riches and pleasures, and they do not mature.

In fact when Jesus was tempted, the cares of the world is the one factor the devil tried to impose upon him. But Jesus foreknew what he wanted and to whom he should worship and serve him - "To the God - The Father only"

Matthew 4:8-10New English Translation (NET Bible)

8 Again, the devil took him to a very high mountain, and showed him all the kingdoms of the world and their grandeur. 9 And he said to him, “I will give you all these things if you throw yourself to the ground and worship me.” 10 Then Jesus said to him, “Go away, Satan! For it is written: ‘You are to worship the Lord your God and serve only him.’”

Upon him, for He cares for you:

Jesus is the only person who could bear our sorrows and the one who cares. His comforting words delights our souls, when he said in Matthew 11:28

Matthew 11:28-29King James Version (KJV)

28 Come unto me, all ye that labour and are heavy laden, and I will give you rest.

29 Take my yoke upon you, and learn of me; for I am meek and lowly in heart: and ye shall find rest unto your souls.

rather than to suffer and get choked by the worldly cares one has to go to Jesus to find the true meaning of life.

Peter also says about the knowledge of God and what it does to a believer in 2 Peter 1st chapter...

2 Peter 1 New English Translation (NET Bible)

Salutation

1 From Simeon Peter, a slave and apostle of Jesus Christ, to those who through the righteousness of our God and Savior, Jesus Christ, have been granted a faith just as precious as ours. 2 May grace and peace be lavished on you as you grow in the rich knowledge of God and of Jesus our Lord!

Believers’ Salvation and the Work of God

3 I can pray this because his divine power has bestowed on us everything necessary for life and godliness through the rich knowledge of the one who called us by his own glory and excellence. 4 Through these things he has bestowed on us his precious and most magnificent promises, so that by means of what was promised you may become partakers of the divine nature, after escaping the worldly corruption that is produced by evil desire. 5 For this very reason, make every effort to add to your faith excellence, to excellence, knowledge; 6 to knowledge, self-control; to self-control, perseverance; to perseverance, godliness; 7 to godliness, brotherly affection; to brotherly affection, unselfish love. 8 For if these things are really yours and are continually increasing, they will keep you from becoming ineffective and unproductive in your pursuit of knowing our Lord Jesus Christ more intimately. 9 But concerning the one who lacks such things—he is blind. That is to say, he is nearsighted, since he has forgotten about the cleansing of his past sins. 10 Therefore, brothers and sisters, make every effort to be sure of your calling and election. For by doing this you will never stumble into sin. 11 For thus an entrance into the eternal kingdom of our Lord and Savior, Jesus Christ, will be richly provided for you.

We should never get discouraged when we are tempted beyond our abilities. For we know that God's word says, "You will have trouble in this world, but be of good cheer for I have overcome it". His word is a delight to our souls, as David says: "If it were not your words, I would have perished in my sufferings". 

We should never forget that, "If Jesus was rejected, neglected and humiliated, we are nothing to bear such humiliations when people say about us, but yet Jesus says, Matthew 18:6 NIV

"If anyone causes one of these little ones--those who believe in me--to stumble, it would be better for them to have a large millstone hung around their neck and to be drowned in the depths of the sea.

So, we can boldly say to these who causes stumble to get away from pulling us down, 

2 Timothy 1:7King James Version (KJV)

7 For God hath not given us the spirit of fear; but of power, and of love, and of a sound mind.

Romans 1:16 NIV

For I am not ashamed of the gospel, because it is the power of God that brings salvation to everyone who believes: first to the Jew, then to the Gentile.