As you go through life, you must make various decisions - about choosing a partner, maintaining a healthy relationship, choosing what to work on, thriving at your work, leading others, becoming a role model parent, supporting certain ideologies and causes, etc. If you wish to live a fulfilling, purposeful and peaceful life, you need to make the right decisions.
To make the right decisions, you need two things - a deep connection with yourself and your personal system that helps you make the right decisions. You can't have those if you are living your life largely focused on the outside.
A regular habit of Contemplation on the right principles helps you look inward, get deeply connected with yourself and enables you to make the right decisions, which leads to lower stress and a more fulfilling life.