Where does the power to live the Christian life come from? This question was proposed to Eric Liddell in the movie, Chariots of Fire. Liddell was asked that question because he seemed to have an inner strength that set him apart from other runners. His answer was, the strength comes from “within.” He was describing an inner strength that God gave him not his own ability.
That scene came to mind when I read Isaiah 40: 30-31 which says,
“Even youths will become weak and tired, and young men will fall in exhaustion. But those who trust in the Lord will find new strength. They will soar high on wings like eagles. They will run and not grow weary. They will walk and not faint.” (NLT)
In the context, we see that God is the only one who does not grow weary or tired (vs 29). Isaiah is encouraging the readers to trust in God instead of their own strength as they considered the possibility of their imminent physical captivity by the Assyrians. They needed to trust in God to find the strength needed to live through those difficult times.
What does it mean to “trust in the Lord” (NLT) or “wait for the Lord” (ESV)?
This concept of “trusting in God,” or “waiting on God,” is described by Gary Smith as “an active dependence on God that patiently awaits his timing with confident expectation.”
John Oswalt describes this concept as “not simply to mark time; rather, it is to live in confident expectation of his action on our behalf.”
So, this passage is telling us that “trusting in God” or “waiting on God” is not being passive but being actively dependent upon God as I eagerly anticipate his action on my behalf instead of relying upon myself.
There is tremendous freedom in letting go and trusting God to lead our lives. An example of this truth is Philip Melanchthon, a friend of Martin Luther. Philip was known to be a terrible worrier. It has been said that there were often times where Luther would have to put his hand on Melanchthon’s shoulder and say, “Let Philip cease to rule the world.” I experience anxiety when trying to rule my life, don’t you? Instead, we need to let go and trust God to care for us in his time.
How does this choice to trust in God give me strength? Isaiah tells us that trusting in God will “renew” those who are worn out. This word is describing the “exchange” of weariness for new and better strength. A strength that only comes from God.
Smith summarizes this concept well when he says,
“This trust in God will replace any false leaning on a person’s own strength. . . This act of trust will enable God to replace human weakness with the powerful metaphorical soaring wings of an eagle (cf. Exod 19:4; Deut 32:11). Their weary legs will be transformed into strong legs that run fast; the fainting person will be able to walk for miles. Trust is never easy, but it is the key to unlocking God’s power. Trust enables people to walk the path (40:31) that God has chosen for their lives (whether it be pleasant or unpleasant) without growing weary or wanting to quit.”
How are you doing this morning? Are you weary? Are you trying to rule your world? Do you need to replace fatigue with God’s strength?
Father, thank you for the amazing promise to exchange my weariness with your strength. This simply comes from my choice to stop depending upon myself, trust in you, and your plan for my life and is demonstrated by yielding to your leadership. Help me to choose to trust you today and may my life reflect such trust in you.
Following Jesus with you,
 Gary Smith, Isaiah 40-66, vol. 15B, The New American Commentary (Nashville, TN: Broadman & Holman Publishers, 2009), 122.
 John N. Oswalt, Isaiah, The NIV Application Commentary (Grand Rapids, MI: Zondervan Publishing House, 2003), 448.