Why is knowing this important? The main reason is that if you don't realize it you may spend way too much time trying to please others or follow someone else's ideas about how you should live. They may think they should have some control over what you do or say but that is totally up to you. Like everything else about your life, it will always come down to what you believe and feel in your heart and gut is right for you.
Because of all of the sights, sounds and opinions of others that we are continuously bombarded with, many people believe they need to fit in and focus on pleasing others rather than following their own hopes and dreams. They believe in competition and survival of the fittest. They think you have to work hard to get what you want. The truth is you do not really need to work hard for anything or suffer at all unless you believe it is necessary to make you "deserving" of what you want. You certainly are not required to do anything simply to please someone else. You can never serve the greater good by doing anything you don't "have your heart in". The best advice is to let your heart be your guide and appreciate every good thing that flows into your experience. The challenge is to keep any fears or worries at bay and chase them away with love and joy in the wonder of your existence as an individualized character in this life adventure.
As you begin to realize that you create your own reality by what you chose to believe in you will learn to be intentional about your creation and become skilled at using your emotional compass. We can alter the future in very significant ways. A new age has begun and we are responsible for shaping how it will unfold.
You came into this life experience with the primary intention of having fun with an adventure in 3D time space reality. You are here to learn how to master your skill of creating / designing a world ever more in line with your hopes and dreams. Your work is to manifest an enjoyable and satisfying experience for yourself. As you get proficient at fulfilling your inspirations and dreams you will positively affect all of material creation. You are the Designer of Reality™. The future is up to you.