(When should I start preparing to change jobs? As an ordinary person, do I really have a so-called good job that is destined for me? How can I know whether this industry is suitable for me? Joining an entrepreneurial company, is it true that retirement at the age of 30 is just around the corner? The same thing, why? Some people write mediocrely, some people write magnificently, and they learn step by step to become slash youths.)