Excerpt from Morning and Evening by Charles Spurgeon

"For my strength is made perfect in weakness" ( 2 Corinthians 12:9 )

 A primary qualification for serving God with any amount of success is a sense of our own weakness. When God's warrior marches forth to battle boasting, "I know that I will conquer; my own right arm and my conquering sword will get me the victory," then defeat is not far away. God will not go forth with that man. He who reckons on victory in this way has reckoned wrongly, for "it is not by might, nor by power, but by my Spirit, saith the Lord of hosts" (Zechariah 4:6). They who go forth to fight, boasting of their prowess will return with their banners trailing in the dust and their armor stained with disgrace. Those who serve God must serve Him in His way and in His strength, or He will never accept their service. He casts away the mere fruits of the earth. He will only reap that seed sown from heaven, watered by grace, and ripened by the sun of divine love. God will empty out all that you have before He will put His own into you. The river of God is full of water,  but not one drop of it flows from earthly springs. God will have no strength used in His battles but the strength which He Himself imparts. Are you mourning over your own weakness? Take courage, for there must be a consciousness of weakness before the Lord will give you victory. Your emptiness is but the preparation for your being filled, and your casting down is but the making ready for your lifting up.