blood lying on my beaten path

Like any other morning, I set the intended distance on my iPod to 4 miles. Uneventful, are the first 2.4 miles. And, randomly, as if someone threw a rock in the end of my path sending ripples my way, I stumbled and fell like a toddler failing its first steps.
I rolled to my right.
Stun still holding me, I lay for a moment then, quickly check my iPod for damage.
"Someone had to have seen that," I think.
"Get up," I say.
Standing straight, I wince and look at my knee. It's bleeding. There is a pea size, perfectly round, wound on my palm; probably from that damn pebble I tripped on; scraps mark my right leg and arm... my elbow throbs.
"I am going to finish this run," I think.
The next quarter mile hurts, but my blood pressure quickly increases, and it's all numb, so I complete my 4 miles.
400 meters to go, says my running partner.
Blood has dripped and dried on my shin.
300 meters to go...
My pace quickens.
200... 100... finished.
As I walk, I begin to limp. My knee stings. BAD.
Blood is clotted... caked on the largest of the scraps. It hurts.
I can't get home fast enough.
I sit. It stings harder.
I wipe it clean with a wet rag...
I pull out a tiny piece of gravel from my knee.
OUCH.
Don't I feel stupid...