Kevin DeYoung in Just Do Something (pp. 47, 48):

We obsess about the future and we get anxious, because anxiety, after all, is simply living out the future before it gets here.

We must renounce our sinful desire to know the future and to be in control.  We are not gods.  We walk by faith, not by sight.  We risk because God does not risk.  We walk into the future in God-glorifying confidence, not because the future is known to us but because it is known to God.  And that’s all we need to know.  Worry about the future is not simply a character tic, it is the sin of unbelief, an indication that our hearts are not resting in the promises of God.