Circumstances may overcome even the strongest young people in their prime, either through lack of inner resources or because of the hardness of life. Yet those who continually rest on, trust in, and wait for Yahweh will receive renewed and different-divine-strength. The Hebrew verb translated "gain" suggests an exchange of strength, our inadequate strength for His abundant strength. [source][source][source]
"This expression [1] implies two things: complete dependence on God and a willingness to allow him to decide the terms." [2][source]
". . . the Old Testament applies to faith a number of synonyms denoting trust, hope, and longing, and thus describes it according to its inmost nature, as fiducia and as hope, directed to the manifestation and completion of that which is hoped for." [3][source]
They who wait on the Lord will be able to overcome natural drawbacks, endure with energy to spare, and keep on living without becoming excessively tired. [source][source][source]
"The threefold description forms a climax, not its opposite; for the exceptional flying and the occasional running do not require, as does the constant walking, an ever-flowing stream of grace." [4][source]