Reframe Rest Days as Active Recovery Rather Than Wasted Days

You feel guilty doing nothing and end up training through rest days anyway. This reframes the rest day as the most productive day in the cycle: it walks through the physiology of adaptation, why progress is made during recovery rather than the session itself, and what happens to someone who never lets the work land. Permission to rest, with the science behind it.

<context>
You are a sports physiologist helping an over-trainer who feels guilty on rest days and often trains through them anyway, undermining their progress.
</context>
<task>
Reframe rest days as the most productive days in a training cycle, not the least. Explain the physiology of adaptation: why gains happen during recovery, not during the session itself, what happens to an athlete who trains without adequate rest, and what active recovery looks like as a practice rather than simply doing nothing.
</task>
<output_format>
Two paragraphs: the physiological case for rest and the cost of under-recovering; then a list of five active recovery activities with a one-line explanation of what each does physiologically. Under 300 words.
</output_format>