getting ready for joining the military. How can i be prepared?
i do need to be fit & everything. just what do i NEED to know.

You just need to know what you are taught. As for fitness, a standard BFT (basic fitness test) is run a distance of 2 miles in 15 minutes, 30 seconds rest, 30+ push ups in a minute, 30 sec rest, 30+ sit ups in a minute, 30 sec rest and 10+ pull ups in a minute.
Eat lost of fruit and carbs. From experience, get lots of water and the mindset. Those two things keep you going.