"If" by Rudyard Kipling was said to be inspired by Sir Leander Starr Jameson, who led the British to overthrow the Boer government in 1895. This didactic poem focuses on the virtues of manhood and leadership, emphasizing stoicism and righteousness.
In the second stanza, Kipling uses the metaphor of "worn-out tools" (line 16) to refer to the strength a person must conjure up to rebuild his life once it is broken. Those tools consist of the human potential all men have when faced with failure. Specifically, the tools could become endurance, patience, and fortitude. When all looks lost and one feels everything he has worked for and given his life for is destroyed, a virtuous man will take those tools and find the strength to use them once again.
Therefore, endurance, being able to go that extra mile when one is exhausted; patience, being willing to wait for results; and fortitude, being able to bear adversity with strength, become tools necessary for life.