But they that wait upon the Lord shall renew their strength; they shall mount up with wings as eagles; they shall run, and not be weary; and they shall walk, and not faint.
Isaiah 40:31

It is vitally essential to remember that we need to have our strength and courage renewed daily. Be strong in the Lord: seek His strength at the beginning of each day—"those who wait upon the Lord shall renew their strength" (Isaiah 40:31). God does not impart strength to us wholesale: He will not give me strength on Monday morning to last through the week. No, there has to be the renewing of our strength, and that strength has to be drawn from the Lord by the actings of faith, appropriating from His "fullness." The enemies we have to contend with cannot be overcome by human wisdom and might. Unless we go forth to the conflict continually looking to Christ for all needed supplies of grace, deriving all our vitality from Him, we are sure to be defeated.
~ A.W Pink

They will walk and not be faint,

Their pilgrimage may be arduous; the road may be long and rugged; often up steep ascents, and down into deep and rocky crags, where every step is a labor—but they shall not lose heart or hope; they shall not swoon, nor halt, nor turn back—but go forwards, sustained by a power greater than their own!

~ John Angell James