I was raised in a very religious family. Belief was something I took for granted. I didn't discover its radical underpinnings until I was in my senior year of high school. We were reading Kierkegaard and this passage really hit me- "belief is the edge of madness" (paraphrased).
It made sense. To believe something is to risk everything else, to make that terrible choice of forcefully limiting your choices. I realized belief was a powerful thing and not something you were born with but had to discover and develop. This thought grew and pushed me to reconsider many of my "core" beliefs. I realized I didn't believe the things I was supposed to believe. It kinda freaked me out at the time.
I define a belief in a somewhat existential/Aristotelian way- your actions manifest your beliefs. You can say or think whatever you want but if your actions don't back that up then you don't believe those words or thoughts.
So if we want to change our actions we have to become true believers. This requires a blend of will, mediation and practice. We can direct our words, thoughts and actions but it isn't easy. We aren't true believers if our entire beings aren't aligned around what we supposedly belief. Without alignment our beliefs start to wither and weaken. Their influence wanes and we eventually lose them altogether.
Belief goes deep, beyond the conscious mind. It resides at the core of our beings. As our beliefs bubble up into thoughts, words and actions they often become diluted or compromised. Usually it's fear and sloth that do the most damage- what will people think, I'm scared, why should I bother, there's something else easier to do, I'm tired, etc.
The human beings that have changed the world, in big or small ways, have this in common- they are true believers. Their entire beings are focused around their core beliefs. My theory is that this is the result of years of hard work (will, meditation and practice) more than any moment of clarity. I'm sure some people have life changing moments but from what I have seen most people don't realize those moments until later. Only when they look back do they see the moment they crossed the horizon and began living an aligned life- beliefs, thoughts, words, actions.
My goal is to live this aligned life. I've got a ways to go but it feels good to have a destination.