The world around you is a perfect manifestation of what you believe to be true.
As you change what you believe to be true, the world around you changes as well.
Sometimes the connection isn't obvious. Here's why:
Most of us have conflicting beliefs, and some beliefs are more powerful than others. Often, these more powerful beliefs require more self-discovery to identify.
Also, when your beliefs on an issue are neutral, then the beliefs of other people involved in a situation will control how that situation unfolds.
The only way to prove this for yourself is to take the time and effort to change what you believe on a number of issues, and track the changes that take place in your life.
There are many techniques for changing what you believe.
Affirmation, visualization, prayer, self-hypnosis, NLP, EFT, and a wide variations of each.
Pick one, and work with it for a few weeks. Track your results, and you'll see the connection.