1. You'll be a Happier Person - Ultimately, this is most of our individual goal. It is to live a happy life. With constant self-development, this will be an eventual result of striving to improve yourself and your environment.
2. Better people skills - Improved relationships - As the saying goes - "No man(or woman) is an island", we cant go through life without having to interact with other people. With self development, we learn to how create a more harmonious way of interaction. We become more socially-aware and socially-competent, leading to more mutually beneficial, productive, and happier relationships.