Well, to start off with, you have to take the initial strength test when you get to boot camp, during receiving week, before you even start training, so there's a mile and a half right there.
After that, you'll run every single day, generally from anywhere between 1-5 miles depending on what other PT you are doing that day. You'll also spend the rest of your day running to obey orders and commands all around the squad bay and depot, so you'll get plenty of time in.
It's not distance that gets worked up so much as pace does, so you'll start off a bit slower and work your way up.
You'll also do 5, 10, and 20k humps (Which is long mountain hikes with full gear and packs) during phase 2.
Obviously, you'll have to do 3 miles for the PFT before you graduate, you'll also do a "Moto run" the day you graduate around the whole base, usually with the base general or the Regimental Colonel leading, which is 4-6 miles, depending on where you attend boot camp.
