A perfectly round door, like a porthole, painted green with a shiny yellow brass knob in the exact middle.
Affected by the books I read in my adolescence, this description of a door (from “The Hobbit”) perfectly captures what my high school biology teacher very boringly described as “a receptor” in the brain.
Mr. Domizio said that the hormone messengers in your system are shaped in unique ways, and would only fit into the proper receptors in the receiving cell – like a lock and a key. Too dull – and too simplistic.
Instead, I think of the receptor as a Hobbit door, and the hormone as a dwarvish visitor. There’s a hobbit inside the door, comfortably curled up with a book and a pot of hot tea, and the hobbit is inclined to assume that every knock on the door comes from Lobelia Sackville-Baggins, come to steal a few more silver tea spoons – so he won’t answer, just in case.
Now, if you hit the “minus” sign next to the map to draw the view up from the microscopic to the living-room view, you can see two toddlers.
One is Baby Barbara. She toddles lurchingly across the room to the arms of her delighted mother – her first attempt at running. Deep within her, the hobbit door is closed tightly – but there’s a cracked window, too. So the hobbit inside can hear the voice calling. “Hey – it’s Kili and Fili, the coolest and cutest of the dwarves, come to hang with you!”
And the hobbit goes to the door in delight and lets in his guests and they have a party and there is joy and active endorphin receptors, and baby Barbara thinks that running is pretty great.
The other toddler is Baby Pru. She toddles across the room to her delighted mother, but the window next to the hobbit door is sensibly sealed. Kili and Fili get swept away before attracting the hobbit’s attention, and the hobbit pours another cup of tea and turns the page, happy in inactivity. Baby Pru gets no endorphin rush and is content to sit in the lap of The Mother.
Every time Baby Barbara uses her muscles, she gets a little buzz from endogenous morphine. She begins to feel good when she exercises. More and more dwarves visit the increasingly pleased hobbit. Barbara begins playing basketball because it feels good to do so – and it feels bad and stiff and leaden NOT to.
Baby Pru gets no buzz. She remains comparatively inactive. Over time, leaves blow up against the door. Every spring, pollen season adds a rim of grime around the door, and every fall the grit of autumn fills microscopic cracks in the wood. Knocking visitors of any persuasion are unable to get any attention. The hobbit, well-stocked with books and tea, hangs out. Exercise brings no joy; no endorphins make it through.
Ultimately, Barbara runs marathons and Pru runs a laptop computer.
Can the closed door be cracked open? Is there a way to break through 58 years of the “No Visitors” sign on the gate? Will I EVER feel joy from exercise??
I think that every knock at the door – every time I exercise and the endorphins are released from my muscles into my blood stream – a layer of grit and dust falls from the door. If I exercise enough, the knocks on the door will crack things open faster than road grit can clog it up again. So if I send ENOUGH dwarves to bang on the door knocker, surely at some point the hobbit will give up and open the door and then the larder will be well and truly raided…
Joy. From exercise.
It hasn’t happened yet. I’m still at “satisfaction” for exercising, not a gentle euphoria. When I finish trotting up and down the stairs for six endless minutes, I’m proud to have done it… but still tired. Still unjuiced by it. I’m not yet to the point where I feel uneasy or twitchy if I DON’T exercise. I’m waiting for that day, though. I’d really like to enjoy this, instead of constantly needing determination to get my cardio done. Christ, I dislike the cardio interval training.
But if you will recall, I’ve often referred to Barbara as my Gandalf, and Gandalf was the one who got Bilbo to open the door… So in J.R.R. Tolkien we trust!