A friend of mine, a fellow brother in the Body of Christ, often says "The Lord willing", or "God willing" about events that will come his way in the future. He referred to the above passage in the Epistle of James in the New Testament.
I didn't find rest in those statements, because we have many promises in Scripture about a good, hopeful end for ourselves, and we don't have to wonder:
"For I know the thoughts that I think toward you, saith the LORD, thoughts of peace, and not of evil, to give you an expected end." (Jeremiah 29:11)
In the proverbs, we learn:
"But the path of the just is as the shining light, that shineth more and more unto the perfect day." (Proverbs 4:18)
How about the promises we have in the New Testament:
"What shall we then say to these things? If God be for us, who can be against us?" (Romans 8:31)
"Nay, in all these things we are more than conquerors through him that loved us." (Romans 8:37)
And let's not forget this wonderful passage:
"Many are the afflictions of the righteous: but the LORD delivereth him out of them all." (Psalm 34:19)
Paul the Apostle would claim the above promise for himself in his final epistle, the his second letter to Timothy:
"Persecutions, afflictions, which came unto me at Antioch, at Iconium, at Lystra; what persecutions I endured: but out of them all the Lord delivered me." (2 Timothy 3:11)
So, whats going on?
Let's consider the audience based on previous sections of the passage.
First, James writes:
"4Ye adulterers and adulteresses, know ye not that the friendship of the world is enmity with God." (James 4:4)
Believers in Christ Jesus are no longer sinners. They are saints, their are beloved children (cf. Romans 8:15), heirs of God and joint-heirs with Christ Jesus (Romans 8:17).
Also, keep in mind that James writes his letter "to the twelve tribes scattered abroad" (James 1:1).
He is writing to a Jewish audience, and there are Jews who believe in Jesus, and there are Jews who do not believe in Jesus yet--and there are Jews who are trying to hold onto the law while believe in Jesus. It cannot be that way.
Hence the term "adulterers" in James 4:4, and why James refers to double-minded twice in his letter (James 1:8; 4:8)
James' exhortation is to unbelieving Jews, or to Jews who are caught between Moses and Christ Jesus, not settling in believing on the Son of God fully.
Also, bear in mind that James is indicting those who boast about their future, who declare based on their own efforts and intellect that they will "do this or that". James is not writing about believers in Christ Jesus. We can know God's will for us, in fact:
"Beloved, I wish above all things that thou mayest prosper and be in health, even as thy soul prospereth." (3 John 2)
"Rejoice evermore. 17Pray without ceasing. 18In every thing give thanks: for this is the will of God in Christ Jesus concerning you." (1 Thessalonians 5:16-18)
We can know and believe God's will for us. We do not have to fear the future, nor should we fear that our lives will be lost or taken from us all of a sudden. We have Jesus, our High Priest Forever, and all the blessings which come with Him (Ephesians 1:6).