Spoke on James 4 on Sunday.
I think this is the verse that sheds light on the chapter.
"14 Why, you do not even know what will happen tomorrow. What is your life? You are a mist that appears for a little while and then vanishes.
You don't know the first thing about tomorrow. You're nothing but a wisp of fog, catching a brief bit of sun before disappearing."

You know that concept, puts everything in this passage into perspective. Perhaps everything in life!
What James is saying here, and it follows on from chapter three...our contentment should not be based on our circumstances. But the truth is, if we are honest, and if I am honest or frank....contentment for many of us so dependent on our circumstances, someone said to me the other day, "Just when I declare my state of happiness a figurative pigeon drops one on my shoulder"

You know it might be quite depressing to think of your life as just a vapour, like mist, quickly forgotten.
Don't be depressed...because God actually brings meaning to this mist of a life. and that has been the whole point. when we weigh up this life, without God, it is a mist, nothing. with God, it is the importance he places on us, which gives this life meaning.

Its not that God does not want us to make plans, and be wise...and think about our futures...
but the important aspect is to recognise God in the midst of those plans. If the Lord wills it, as the message puts it, Instead, make it a habit to say, "If the Master wills it and we're still alive, we'll do this or that."
I have to say, I am amazed at how many christians make massive life altering plans and dont even acknowledge God in any way. Acknowledge God, and He will direct your paths.