+1 with LongAgo. There are a ton of threads regarding how to get in shape.
To be honest, and not trying to be rude, but getting in shape is not rocket science. Run in the rain, run in the heat, run at 6:00 a.m. after you went to bed at 1:00 a.m.
~ That is reality for your next year. You will be up to 1:00 writing a paper/studying for an exam and expected to do PT at 6:00 a.m., which means, even if you live on campus and just roll out of bed, you are rolling out at 5:15, or 4 hrs of sleep. On top of that it could be drizzling, which means your sneaks are not going to have traction like they would on a sunny day.
My DS ran at 4-5:00 p.m. and ran 2 miles. He did this because where we live that is the height of the heat. His goal was to always be under 7 minutes. His Dad was ADAF, and the mindset was training in the extremes would help him from an endurance perspective. 2 miles at less than a 7 min. mile pace, with the heat index of over 100 and high humidity (burning his lungs with every step due to air quality), than running at 6:00 a.m. with lower temps and lower humidity would result in a faster time. Same goes for running with sleep deprivation. If you are tired, than it takes a few minutes to get out of the mental fog, and that can equate to the seconds you need to shave off your running time from a pass or fail aspect.
DS did the entire PFA in order everyday. He had someone in the family be there to watch his form for push up and sit ups. If he did not meet the form, we didn't count it. That is a biggie. If you search these forums @ end of Aug/early Sept. you will find out scholarship cadets/mids fail because their form was wrong according to ROTC stds.
~ Doing 50, but only 30 are correct form, you will not only waste energy, but end up with the same cadet/mid that only could do all 30 in the correct form. Form matters.
Every ROTC unit is different when it comes to PT. My DS was AFROTC. PT included butterfly kicks and variations of pushups. (side arm/clap) 2x a week for PT. His unit also allowed cadets that maxxed the option to skip PT and train on their own, no 2x a week PT training at 6:00 a.m.. They only had to show up for the PFA exams. Of course, that really meant 1 semester off because the next semester they were either a PT instructor, a flight instructor, etc., where they now HAD to show up for PT due to their job description.
You can do this. You have...what...4-6 weeks before showing up. Most units do the PFT 5- 7 days after arriving. Download the PFA. ask someone in the house to read it and seriously look at the form. Let them count. No easy passing, bad form and it will not count. After you do that, don't quit. Do butterfly kicks. 2 weeks out buy a good pair of running shoes. Not the time to go cheap. Two weeks out because you want to break them in. If you don't break them in, your feet may feel the pain and your run time will be slower.