@kennethamy,
There are basically two kinds of factors that determine your choice:
Group 1: desires (intentions)
Group 2: all other factors
When all these factors are present, then the choice is fixed - it will be materialized as it logically follows from these factors and there is
nothing that could change it. Regarding Group 1, the different desires are like different forces that influence you in different directions and when you add up all their influences you get a resulting force and direction, which means that the direction of the strongest desires will prevail but it may be modified by the weaker desires. The Group 1 factors give your choice intentionality, unless Group 2 factors thwart the direction of the Group 1 factors (in that case we don't say that our choice was intentional but that our intentions were thwarted, resulting in a different action than the one we intended/desired). Group 2 factors are anything you can imagine (other than desires/intentions) that influences the choice but the important thing about them is that they definitely don't make your choice a free one, because they are unintentional - they are the unintentional contribution to your choice.
So your choice is determined by your desires (intentions) and possibly by various other factors (which are unintentional). In order to control your choice you would need to control these factors. But how would you control them? They themselves are determined by other Group 1 and Group 2 factors (in a preceding choice), and so on.
I should add, in the light of quantum mechanics which suggests that some events are not determined by causes (that is, they are at least partly uncaused), that maybe even all the Group 1 and Group 2 factors will not definitely determine your choice. That means that your choice contains an uncaused component. This component, however, cannot make your choice a free one either, simply because it is not caused by anything, including you. So you could go against all existing factors but without control of your action.