hike?

Hmmm, I don't know if I should. 8-12 miles a day, from 6am - 10pm carrying 30lbs of equipment for 5 days.... yes? no? I don't know? They say we need to be physically in good condition, but what does that mean? My chest - sternum? - idk the middle of my rib cage at the front of my chest, it hurts when I run too fast or work out too much or something, and idk if that's just me or if that's an issue. I play quidditch, but we get breaks, and we play for 30min tops at a time. I want to challenge myself, but I don't want to be the one holding everyone back. I heard 2 miles an hour is good, but ehh WHYYY! Wish I had friends who will hike for a week. But no one I know is fit enough... and the ones who are, I'm not buddy-buddy with. Great dilema, huh?