You accidentally burn your finger on the stove, this is detected by the nerves that send nerve signals to the brain that signifify pain. In the brain those signals create an incredibly complex reaction in the brain that cause you to withdraw your hand. For a "philosofical zombie" - an awareless automaton - that is all that happens.
For an aware being, this is followed by an "experience" of pain.
How does this experience of pain arise? There is an action and reaction in both the aware and the unaware, an automaton does not EXPERIENCE pain, even though reaction and consequent actions are identical.
Let us focus on the experience of the aware observer - where does it start? If it is in the brain, we can reduce it to physical effects, in which case our automaton could replicate it. Plus, at what point does the feeling arise? It's clearly not in the hand itself, nor in the nerves. But nerves are an extension of the brain. We have a part of the brain that handles pain, but why should those particular brain cells cause a painful feeling to arise? These are just like all the other cells in the brain, just differing in connections.
Why would the activation of some cells cause pain to arise? If it is due to the connection that cause our brain to decide that this was a negative experience, then this would imply that the feeling arises when the pain center sends signals that it is stimulated to other parts of the brain. Then does the feeling of pain arise in the cells connecting to the part of the brain dealing with pain? If so, by what mechanism do those parts of the brain cause the feelings to arise?
There is no way to nail down a mechanism that isn't physical and anonymous (i.e. doe not know the context of what it is connected to), and trying to claim that inanimate objects are self-aware is a bit of a stretch. We reach the conclusion that there is no good way to describe aware experience arising from the physical.
Nor do any simple metaphysical notions of "soul" work, as any metaphysical system run into similar issues (if there is a soul, then by what process does it give rise to awareness)