Gentlemen, Ladies,
I'd like to offer some candid advice for anyone going on these courses based on first hand experience and second hand discussions. Not looking to derail this but it's important.
MANY of you are showing up out of shape, specifically for marching and rucksack marching. People have all kinds of reasons why they're out of shape but at the end of the day the why doesn't matter.
What matters is people are falling out of PT and falling out of marches. This often leads to trips to the medics where people try to get medical chits saying no running, no ruck marching, no carrying kit. You follow everyone around in a vehicle or walking like zombies behind your peers marching. It's a shitty way to go through your course and a shitty way to start your military career. It sets your whole course up to be a back and forth about why you can't do anything.
You'll be marching everywhere you go. And just because you do PT in the morning doesn't mean you won't have a long march to do in the afternoon. A 5km march to the range carrying your kit, or a 10km march to your sleeping site.
Running is great but practice walking quickly with a heavy backpack. Go for a walk in the woods with a sledge hammer to simulate a rifle. Build up the muscles on your legs and arms.
Good luck.