The king shall have joy in Your strength, O Lord;
And in Your salvation how greatly shall he rejoice!
SINCE IN ANY CONTEST BETWEEN THE "HEAD" AND THE "HEART," THE HEART ALMOST ALWAYS WINS, IT IS VERY IMPORTANT THAT OUR HEARTS BE GIVEN TO GOD. God gave us all three of the parts of our minds -- our intellect, our emotions, and our will -- and our emotions cannot be safely neglected. If we don't bring the positive power of our emotions to bear upon our spiritual lives, we will find it difficult, if not impossible, to serve God faithfully and consistently. If our feelings have gotten out of hand, they can be our enemy and pull us away from God. But that need not be so. There is no good reason why our feelings can't be our ally. Working with the intellect and the will, the heart can help us.
In his prayer, David said that "the king shall have joy in Your strength, O Lord; and in Your salvation how greatly shall he rejoice." It is a joyous thing indeed to contemplate God's strength. But there is another side to this truth. The very joy we are able to have in God's strength is also the main source of our own strength! As Nehemiah said to the people of Jerusalem, "Do not sorrow, for the joy of the Lord is your strength" (Nehemiah 8:10). Strength of character is always more than the product of raw intellect or brute willpower. Our affections must be involved also. And if it is spiritual strength we're interested in, then the feeling of joy is especially important. There is no stronger person than the one who fully feels the joy that can be found in God.
There will certainly be times when commitment to God will require us to say "No" to unworthy thoughts and words and deeds. But the key to doing this consistently is not simply the development of a stronger will. In the long run, we won't be able to say "No" to what is wrong if we don't have a bigger "Yes" burning within us for what is right. We must want what is good, and we must want it with all of our hearts. Like our Lord who "for the joy that was set before Him endured the cross" (Hebrews 12:2), we must be moved primarily by joy and hope. The prospect of one day seeing God's face must be the main part of our strength.
"It is vain to contend with anything that hath the power of our affections in its disposal; it will prevail at the last" (John Owen).