You did not do your research on attire for this trip...
Oh boy! I'm starting to shiver.
That is your body attempting to maintain homeostasis in your body. There is a negative feedback loop occurring for thermoregulation to maintain the body temperature at a certain set point for you to survive.
That still doesn't explain why I'm shivering so much.
When your body temperature drops, this is the stimulus that causes the receptors in your skin to send a message to your brain, the control center, through an afferent pathway.
When does it get to the part where I become a popsicle!!!
Then, through an efferent pathway, the control center will send a signal to an effector, which will try to reverse the change back to the set point.
What would the effectors be for me?
Since you are cold, your effectors would be your muscles shivering and your blood vessels constricting to produce and preserve body heat.
Now I don't feel as cold anymore, thanks to the...