One way free will can exist in a deterministic world is by interpreting it as an emotion. Similar to anger, happiness, pride, etc.
Anger is associated with actions of recklessness. Happiness with actions of play.
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I claim free should should be associated with the feeling of taking actions aligned with internalized principles, especially when those are at the cost of comfort, safety, or status.
Eg: Choosing to run faster when one should have given up. (obviously can't will oneself to run faster than physically possible. But the internal experience is a going to feel like free will in some way)