Some days I find myself under a cloud of anxiety. Things can pile up to the point that I can't quiet my mind enough to think clearly. And that's the problem, isn't it? Anxiety, worry, fear, withdrawal, etc. . . . all have the effect of causing us to think like the sluggard in Proverbs; "There is a lion in the streets!". Indeed, as Andrea Burke says, we start to mull over "a lot of things that may or may not be true." No wonder Paul encourages us in Colossians to think on things that are, "true".
At times, even when we're seeking direction from the Holy Spirit, we can succumb to a "spirit of Fear" or discontentment masquerading as piety. God promises us "rest" when we come to Him, and we need to remember that when we're unsure of a decision.
I read two great articles recently about this, and if you have 10 minutes today, I encourage you to read them. The Gospel should give us great courage as we face the trials of our life.