This quote is a testament to the power of self-perception and self-determination. The idea behind it is that our actions, behaviors, and attitudes are not predetermined or fixed, but rather they are shaped by our own choices and beliefs about ourselves.

When Sartre says "The coward makes himself cowardly," he means that an individual becomes a coward not because they are inherently so, but because they choose to act in a way that is cowardly. They may do this out of fear, insecurity, or a lack of confidence in their abilities. They see themselves as a coward, and thus, they behave as one.

On the other hand, "the hero makes himself heroic" suggests that heroism is also a choice. A person becomes a hero not because they were born with some sort of heroic trait, but because they choose to act courageously, selflessly, or nobly. They see themselves as a hero, and so they behave as one.

This concept can be applied in today’s world and in personal development in many ways. In a society that often feels pre-determined by our circumstances, this quote is a reminder that we have the power to shape our own identities and destinies. For instance, if you see yourself as a victim, you’re likely to remain one. But if you see yourself as a survivor or a fighter, you’re likely to overcome your adversities.

In terms of personal development, this quote encourages self-reflection and self-awareness. By understanding how our self-perceptions shape our behaviors, we can make conscious choices about who we want to be. If we want to be more courageous, we can choose to act bravely even when we’re scared. If we want to be kinder, we can choose to act with compassion even when it’s difficult.

In conclusion, the quote emphasizes that our identities are not fixed or inherent, but rather, they are constructed through our own choices and actions. This is a powerful concept that encourages personal growth, self-determination, and responsibility for our own lives.