Sankhara meditation

Could someone explain to me how to meditate in order to see how the sankharas can be manipulated and changed so to not feel that the current situation is fixed and a must and helpless. I read somewhere that this was possible and in my personal practice that would be really helpful. From what I have heard there are 3 Sankharas : Kaya,vaci and citta or mano. How do i manipulate them during meditation and in what way do i manipulate them so I can see that there is free will and that I am not helpless could you describe with what particular technique do i manipulate or change a particular sankhara, I really need to understand it so that I can feel that these things are not a must because it seems like a must for me. (especially my feelings seems fixed and like a must) Perhaps my perceptions are messing things up to so I really want to feel that I have power over my situation by direct seeing that these things are not a must and get be manipulated and changed beacuse now it seems like a must. But I would appreciate all possible advice you could give not just about manipulating feelings during meditation but all other Sankharas or aggregates and the technique used and which sankhara or aggregate is manipulated during that particular technique. Also 1 more question. Are sankharas volitions (things we do uknowingly that can be stopped with free will) to me its like they have power over me is that ultimate truth, Because from my first question as you saw there was Monk that said that theese things could be manipulated that seems like they are not a must and can with free will and skillful attention,mindfulness be stopped if yes please tell me how and please describe how and what is happening and I will try it. Thank you all.