In this book, Kim Hye Nam, a psychoanalyst for thirty years, shares her advice to those of us who have already reached the age of forty. She says that if she has one regret in her life, it is that she was too hard on herself and treated life like a homework assignment. As a doctor, mother, wife, daughter-in-law, and daughter, she was always overwhelmed with obligations and responsibilities, trying to fulfill them all, and missing out on the pleasures of life. Then, 22 years ago, at the age of forty-three, he was diagnosed with Parkinson's disease. She realized that without her, the house, the hospital, and the world would not function properly. It made her see the people who cared for her and reminded her of the important things in life that she shouldn't miss. So, at the age of 40, she has only one thing to say to those who want to live a life without regrets. "When one door closes, another one opens. So stop thinking about it and just have fun!"

In this special edition of the book, which was published in 2015 under the title "Why I'm Having Fun Today," and became a bestseller with more than 100,000 copies, the author shares the secrets of life that he realized while working as a psychoanalyst for 30 years and why he can live joyfully despite living with Parkinson's disease for 22 years. In this special edition, the author reveals the things he wishes he could have said to his patients, such as, "The perfect time never comes," "Sometimes holding on is the answer," "Please don't tell me everything hurts," and "The closer you are to someone, the more you shouldn't do something.