It's often said that nothing is impossible, simply restricted by varying degrees of improbability. Understanding that concept and more importantly applying it to remove mental barriers that are keeping you from achieving your goals is a crucial step in your personal and professional success.
Establishing a baseline when developing any project, whether personal or professional, is paramount for measuring progress in any situation. Additionally, the more information that you have to build upon, the more likely that your endeavor will be successful. Understanding your own strengths and weaknesses plays out much the same way.
Charles Darwin famously said that it is not the strongest of the species that survives, nor the most intelligent, but the one that is most adaptable to change. However, to improve your ability to adapt, you must have as much information as possible to ensure that your attempt at evolution is successful.