system
Given the following post, respond as if you're commenting on Reddit:
human
Why do we stretch and why does it feel good when we do? 

It doesn't seem to be something we do instinctively. Yet other animals do it too.

^(I actually sound like I'm 5)
gpt
When your at rest your body slows down and your blood flow decreases. Stretching gets things moving along by causing your heart to beat a bit faster for a few moments. This increases oxygen, blood flow, and waste removal. Making you feel awake and fresh with new energy.  Similarly water at rest can become bland and boring but once it ripples or moves it becomes more alive as do the beings within.