look....relax. when I was preparing for this, i expected a super physical, hard core experience. It really wasn't.
i maybe did a couple hundred pushups over the course of the entire summer--nothing---, my end of beast apft scores were WORSE than the diagnostic ones. If you are even remotely an athlete, you will be fine. if you still feel super hooah about training, just make sure you can do at least 60 pushups (2mins), 65 sittups (2mins), and a 14 min two mile. If you can manage that, then you'll be comfortable.
what people don't expect, is it really is a complete mind game. You're being run by rising cows, who may be doing their first REAL leadership detail. some are good, some really aren't, they're just people, sometimes as backwards as you are. you will do stuff, that seems to have no value (and may actually have no value) like taking out a knowledge book and putting it back ten times--because he said so. Beast isn't perfect, but that's part of the lesson.
don't expect some super hooah pre-ranger school, like all those videos seem to picture it as, expect a sampling of the bs you sometimes put up with in a government institution.... standing in formation for two hours. watching the Fifth powerpoint presentation on your insurance policy, getting yelled at for scratching your nose when you didn't ask permission, taking your stuff off, making it neat and then putting it back on...three times... until your pl liked the location for lunch.
on the flip side, you get to do some fun stuff, you play with machine guns, claymores, M4s, it's an experience.