Cmv. i don't believe in freewill.:
Look at the brain from a physical/chemical perspective. Neurons are fired when we see/smell/hear/touch/taste things. Those neurons interact with other neurons via chemical processes that are well understood. Those neurons interact with more neurons, and so on, and so on... Eventually motor neurons are triggered which cause us to respond to the sensory input. In no part of this process can I see a way to affect the chain reaction of neurons in any way.

Sure, each of our brains is put together differently and that means that each of us will respond differently to similar stimuli. But given the EXACT same situation our brains will react exactly the same way to the exact same stimuli every time. So essentially, you never had a choice.