"我钱包里有一张小纸条，上面写着“如果你不在竞技场上也被揍得很惨，我对你的反馈不感兴趣。”"

Simplified Meaning:

This quote is about only accepting criticism or advice from people who are also putting in the effort and facing challenges, much like you are. For example, imagine you are a soccer player working hard to improve your skills. If someone who has never played soccer tries to tell you how to play better, their advice might not be very helpful because they haven't experienced the difficulties you face on the field. However, if a fellow player or your coach gives you tips, their advice is more useful because they know what it’s like to struggle and succeed in the game. In everyday situations, this means valuing opinions from those who are actively involved and understand your challenges, rather than from those who are just on the sidelines. It can be applied by focusing your attention on feedback from people who have similar experiences and genuinely understand your situation. This helps you grow and improve in a positive way while ignoring potentially uninformed or negative comments from those who do not share your experiences.