No one can keep God's law:
"Therefore by the deeds of the law there shall no flesh be justified in his sight: for by the law is the knowledge of sin." (Romans 3:20)
"Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ, even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law: for by the works of the law shall no flesh be justified." (Galatians 2:16)
It's not about bringing out thoughts into captivity to Christ, or trying to tie everything to Him.
We are to settle every dispute and attack against our minds because of Christ's obedience!
What is this "obedience" specifically referenced by Paul?
"For as by one man's disobedience many were made sinners, so by the obedience of one shall many be made righteous." (Romans 5:19)
We are to rest in the truth that all our sins are put away because of Christ's obedience to His Father at the Cross.
Any fears about the future are put away at the Cross, because Jesus shed His blood and enacted the New and everlasting covenant:
"For this is my blood of the new testament, which is shed for many for the remission of sins." (Matthew 26:28)
Here are the full elements of the New Covenant:
"For this is the covenant that I will make with the house of Israel after those days, saith the Lord; I will put my laws into their mind, and write them in their hearts: and I will be to them a God, and they shall be to me a people:
"And they shall not teach every man his neighbour, and every man his brother, saying, Know the Lord: for all shall know me, from the least to the greatest.
"For I will be merciful to their unrighteousness, and their sins and their iniquities will I remember no more." (Hebrews 8:10-12)