Everything in the universe interacts in some way, all living things require some form of energy provision.
Out bodies are run on cell engines not too different to your car. Sugar (fuel) and air in, water and CO2 out, internal combustion!
Our energy comes from the turning of turbines, ATPase in our mitochondria. So it isnt about free will, it is all about the laws of thermodynamics and energy transfer.
However, free will is an amazing topic and I highly reccomend you read up on determinism.