II Corinthians 10:5 "Casting down all imaginations and every high thing that exalts itself above the knowledge of God. Bringing every thought captive to the obedience of Christ."
If I let my imagination run wild, life would be very sad. Worry would set in my heart over things I could not control. I've learned to catch myself when I start this mind racing imagination stuff. Click. Quote the verse. Realize that God is in control and He is our heavenly Father watching over us more than any earthly father ever could. I then think of times that God has shown His power. It's much better meditating on that power than what imaginations my mind can conjure up.