I realize that not everyone is suitable for such a philosophical question, fortunately I found potential answers in the wise and the eminent dead whose lives I deem to be meaningful. Inquire about the greatest joys and regrets of those whom we admire. Sometimes, we cannot ask them directly for the sake of being diplomatic or because they have passed away. However, inspiring living things always leave marks. Read between the lines. Listen to the unsaid. As we explore their victories, failures and memories, we will find perspective for ourself.
The reflections of fellow peers who embark on self-discovery journey are also worthy of consultation. For example, happy green panda has enjoyed the work by a lifelong learner, an entrepreneur / weightlifter whom was acquainted in Switzerland, a London-based economist, and many others.