Three things determine the way we feel, think and act.
First, our genes and their activity patterns (while we inherit our billions of genes from our parents, we rearrange them ourselves, imagine a large mosaic that gets messed up and reassembled) which in combination with prenatal influences form our character.
Second, all of the positive and negative experiences from our first three years of life. We have experienced them consciously but cannot remember them because our brains were not quite ready for it at the time.
These two, our genes and the early childhood memories we cannot consciously recall, make up the largest part of our personality and to change this at a later stage is really difficult if not impossible.
Third, pre-conscious experiences from our late childhood and teenage and adult years which often influence us imperceptibly but which we are able to recall if necessary, albeit with difficulty. Yet, despite the fact that they represent our conscious existence and can be altered easily, their influence on how we feel and act is limited.
In fact, we are mainly driven by stuff which mostly comes from our experience but is not part of our conscious memory and if so, only intuitively.
So, while awareness and thinking help us to adapt our basic motives of action to existing circumstances and to find alternatives and possible consequences, they are not responsible for our decisions.
The long version: