“Self-discipline begins with the mastery of your thoughts. If you don’t control what you think, you can’t control what you do. Simply, self-discipline enables you to think first and act afterward.” — Napoleon Hill
The value knowledge has is the value you create by using it. If you learn things and forget them, the value is close to nothing. Use your knowledge to solve novel problems. This could either be personal development challenges, consumer problems, or societal problems. Avoid learning for the sake of learning.