To earn a PhD, one must master a specific subject completely and extend the body of knowledge in that field. Getting a PhD requires intelligence, time, creativity, curiosity, adaptability, self-motivation, competitiveness and maturity. One should consider why they want a PhD, their career goals, and what doctoral study and the target field are really like. A PhD does not guarantee prestige, respect, or a job, and should not be pursued just for money or to impress others. However, working with brilliant peers and solving unknown problems can bring the joy of discovery.