Read Psalm 25:21

Thoughts are the thermostat that regulates what we accomplish in life. 

My body responds and reacts to the input from my mind. If I feed my mind upon doubt, disbelief, and discouragement, that is precisely the kind of day my body will experience. 

If I adjust my thermostat forward to thoughts filled with vision, vitality, and victory, I can count on that kind of day.

Thoughts, positive or negative, grow stronger when fertilized with constant repetition. That may explain why so many who are gloomy and grey stay in that mood...and why those who are cheery and enthusiastic continue to be so.

You need only one foreman in your mental factory; Mr Triumph is His name. He is anxious to assist you.

His real name is the Holy Spirit, the Helper. 

Excerpted from Charles R. Swindoll, Wisdom for the Way (Nashville: J. Countryman, a division of Thomas Nelson, Inc., 2001). Copyright © 2001 by Charles R. Swindoll, Inc. All rights reserved. Used by permission.