Mile eight.

I'm training for a marathon. It's in 5 1/2 weeks. And the farthest I've run to date is eight miles.

"Hmmm, it's probably time to step it up, Kellie..."

Yes, you're correct. As I've started to run longer and more frequently, I'm beginning to notice the effects of altitude on my body. While I was in London, I was running a pretty consistent 8:30 mile. I could run 3.5 miles and feel comfortably tired, but not completely wasted.

But then, that was nearly at sea level. Now that I'm back at home in the rocky mountains of Utah, I'm training at roughly 4,000 feet above sea level. That's a pretty big difference, and on my first run after getting home, my body was hating me. I felt like I had to expend twice the effort to run half the distance. I was inhaling but felt like I was getting no oxygen. After two miles, my legs felt like bricks. I was struggling to keep up a 10:00/mile pace.

I'm starting to readjust. But it's clear I've got my work cut out for me.