I would go to an atomic level and say that subconsciously/unconsciously electron (x) 'knows' it is being exchanged (y). I say this because I find an impossibility in x being capable of y and not finding an awareness of y, it must 'know' that exchange is what it must do. The question of consciousness is raised here, and I would doubt Didymos' statement in that the mind 'knows' subconsciously that the heart must beat / one must drive unto destination.
Are we free to slow/stop our heart?
Or to quit ritual habits?
Difficult questions which are kind of answered by the fact that it is possible
to arrange to have one's heart stopped, and we can come to terms with ritual habits and engage in the discouraging of them, but rather more on point they do slip 'out of mind' and into the subconscious more frequently than we might prefer.
Once when I was incredibly stoned I thought that my heart had nearly stopped, and that I had to consciously think of starting it up again, I also found ritual difficult to avoid. Whether these are issues of freedom is slightly like an anamorphic philosophical exercise; I think 'freedom' is a distortion of something(s) far less vague and more precise in their manner, although we could probably find freedom in the picture if we perhaps moved our perception of the topic to another angle (perhaps we would find a lack of freedom in x knowing y and doing it). I doubt that I had any freedom not to engage my heart consciously or subconsciously, there is no part of my body that would allow the stopping of the heart without immense struggle.
My answer to the notion of freedom curtailed by subconscious activity is that our subconscious is far more active than our conscious mind and engages our bodies in activities which it has deemed possible/beneficial/desired, so in a way our conscious freedom is curtailed but that does not negate the possibility that the subconscious is aware of freedom and the exercising of freedom.