A lot of what drives us is dictated by external forces. But you can’t know that everything is determined by fate. Whenever a person first “realizes” everything is determined they get depressed. They get depressed because if there is no free will then what is the point of doing anything. If everything is determined, no matter what you do you will not change anything. The way people get out of this deterministic depression is by believing there really is some spark of free will. That seems to show that the spark of free will is there. That spark will motivate us to change things for the better.
We are just a mass of energy bound up into complex systems. If there is free will it would be based on a property of this energy. What scientists see way down at the quantum level is what they call the quantum effect. This effect is a sort of randomness or non-deterministic causality. If through thought we can direct this effect somehow that would give us the ability for free will.