As my strength was then, even so is my strength now. Jos 14:11
Men sometimes lose heart as they grow old. They say: My intellect will become impaired, my physical strength will abate, my power for service will wane. Yes: but if the outward man decays, the inward man shall be renewed day by day.
Those that wait on the Lord shall renew their strength: whether to war, to go out for service, or to come in for fellowship and rest. Be of good courage, and He shall strengthen thine heart. He shall satisfy thy mouth with good things, so that thy youth shall be renewed as the eagle's. God's angels are always young. The drain of the years is amply met by the inflow of His all-sufficient grace. There is no reason why we should decline in usefulness and fruit-bearing with the increase of years; but the reverse. The last sheaves that fall beneath thy sickle shall be the heaviest; and the width of thy swathe shall be greatest as the angel of death touches thee and bids thee home. The secret lies in wholly following the Lord.
But Caleb did not rely on his strength to win Hebron. Very modestly and humbly he said, "It may be that the Lord will be with me." Not that he for a moment doubted it. Could it be for one moment supposed that the God whom he had wholly followed for eighty years would desert him in the supreme crisis of his life? But he put it thus in the sweet lowliness of his soul, because he counted not himself worthy. The strongest men are they who count that they are helpless as worms; and who put their weakness at the disposal of God's might. To each of us comes the promise of God: "My grace is sufficient for thee; for My strength is made perfect in weakness."