This paper examines the "Paradox of Determinism and Practice": how an agent can commit to physical causal closure while sustaining deliberate practice without reducing it to an illusion. Applying conceptual and phenomenological analysis, we demonstrate that this paradox arises from conflating the absence of physical alternate possibilities with the lack of guidance control. Drawing upon the stochastic accumulator model, neuroscientific timing data fail to invalidate long-term reflective intentions. Furthermore, through interventionist and proportional causation, the macro-level efficacy of practice is established against Kim's causal exclusion challenge. Synthesizing Fischer and Ravizza's guidance control with Merleau-Ponty's phenomenology of the lived body, practice is articulated as expanding the bodily "I can" horizon and transforming interpretive context. Ultimately, following Hobart, causal stability is shown to be the foundational condition for deliberate practice and lived human agency.