Notice that during His earthly ministry, the Israelites asked Jesus: "What do we do, so that we can work the works?"
The emphasis for man is on what man can do for God.
This is the stumbling block for all of us. We want to do for God, just like Cain giving some of the produce from the cursed ground that he tilled, all the way to the Pharisees who added rules and regulations to the Ten Commandments, which had fully declared God's immutable nature and unassailable standards.
The fact is, that our righteousness has to surpass any legalist's standard:
"For I say unto you, That except your righteousness shall exceed the righteousness of the scribes and Pharisees, ye shall in no case enter into the kingdom of heaven." (Matthew 5 :20)
"Be ye therefore perfect, even as your Father which is in heaven is perfect." (Matthew 5: 48)
There is a simple answer to this demand: I can't!
No one can.
"For all have sinned, and come short of the glory of God;" (Romans 3: 23)
So, instead of our trying to do more for God, we need to believe more that He has done it all.
Even Job the distressed understood:
"Who giveth rain upon the earth, and sendeth waters upon the fields" (Job 5: 10)
Through Jesus, God our Father has provided all things:
"He that spared not his own Son, but delivered him up for us all, how shall he not with him also freely give us all things? (Romans 8: 32)
"Blessed be the God and Father of our Lord Jesus Christ, who hath blessed us with all spiritual blessings in heavenly places in Christ:" (Ephesians 1: 3)
Now, believing on Jesus for all things is hard work, in that we are so wired toward doing more, rather than believing more.
Take the example of Elisha, his servant, and the Syrian Army:
"And when the servant of the man of God was risen early, and gone forth, behold, an host compassed the city both with horses and chariots. And his servant said unto him, Alas, my master! how shall we do? 16And he answered, Fear not: for they that be with us are more than they that be with them. 17And Elisha prayed, and said, LORD, I pray thee, open his eyes, that he may see. And the LORD opened the eyes of the young man; and he saw: and, behold, the mountain was full of horses and chariots of fire round about Elisha." (2 Kings 6:15-17)
Notice that the servant "what shall we do?" Elisha prayed: "Open his eyes."
Paul prayed the same prayer for all of us in regards to God's love for us!
"he eyes of your understanding being enlightened; that ye may know what is the hope of his calling, and what the riches of the glory of his inheritance in the saints," (Ephesians 1: 18)
"For this cause I bow my knees unto the Father of our Lord Jesus Christ, 15Of whom the whole family in heaven and earth is named, 16That he would grant you, according to the riches of his glory, to be strengthened with might by his Spirit in the inner man; 17That Christ may dwell in your hearts by faith; that ye, being rooted and grounded in love, 18May be able to comprehend with all saints what is the breadth, and length, and depth, and height; 19And to know the love of Christ, which passeth knowledge, that ye might be filled with all the fulness of God." (Ephesains 3: 14-19)
It is hard for us not to work, but rather to believe, to see that which is not readily visible to our senses, but we are called to that "Work":
"Let us labour therefore to enter into that rest, lest any man fall after the same example of unbelief." (Hebrews 4: 11)
Faith comes by hearing the word of Christ (Romans 10: 17), and that work can be hard for us, especially if we have been geared toward adding something of our efforts to anything that we ask or seek from our Daddy God.
Heed Jesus' words then and now: Believe on Him!