What does Rudyard Kipling mean in his poem if- fill the unforgiving minute with 60 seconds?

In the poem "If-" by Rudyard Kipling, the line "fill the unforgiving minute with sixty seconds' worth of distance run" means that one should make the most of every moment, maximizing the use of time and taking every opportunity to achieve their goals despite the challenges or obstacles they may face. It emphasizes the importance of being efficient and productive in all aspects of life.