James 4:13-14 Look here, you who say, “Today or tomorrow we are going to a certain town and will stay there a year. We will do business there and make a profit.”  How do you know what your life will be like tomorrow? Your life is like the morning fog—it’s here a little while, then it’s gone.
I don’t think that God is trying to say that we can’t make plans for the future. This is saying, however, that we cannot assume that God’s plan is the same. We have to be ready to do His will, no matter the cost.