What does this mean If you can meet with Triumph and Disaster treat those two impostors just the same?

This line is from Rudyard Kipling's poem "If—" and it encapsulates the idea of maintaining emotional equanimity in the face of both success and failure. "Triumph" and "Disaster" are personified as "impostors," implying that they are not what they seem. The speaker urges the reader to treat them both in the same manner, suggesting that one should not be overly elated by success or devastated by failure. Instead, one should maintain a balanced perspective and approach both situations with resilience and composure. This line emphasizes the importance of emotional fortitude and mental toughness in the face of life's ups and downs.