If you see Buddha’s teachings…
He says Mind is everything…
Karma is basically this…What you perceive …the same you think…so when you think it creates Mental fabrications called as “Sankhara”…these fabrications over time become your habit and eventually your character.
What he says basically is that this process can be reversed…meaning your character, habits, fabrications and thoughts can be changed…by changing your perception.
Once you do that…much of what we call life can be controlled…but again…it takes effort and I still believe there is no free will and some amount of determinism is always there…(maybe 30-40%).