Work out in the worst weather.
I don't know where you are from, but trust me the heat and humidity level in Alabama is an issue. Cadets from Maine can't even begin to fathom it. Running down there when it is 85 degrees at 6 a.m and 90% humidity can feel like you're breathing in fire into your lungs.
If you are not from the south, work out at the height of the day in your area regarding heat and humidity.
Last yr it was one of the hottest summers on record for Alabama, if I recall correctly they had @40 days of over 100 degrees...that would equate to you the entire time there. Throw in the humidity and the heat index jumps to 110-115 degrees. Now go in the woods and wear your ABUs with boots and wool socks!
Again if you are coming from places that never saw temps like this working out in it can cause physical stress to your body. Acclimating quickly will be the key, hence, if you work out at home when it is the highest temp your body will be able to adjust faster.
Also acclimate your body to sleep. Granted you want to come home for the 1st few days be a teenager and stay up to 2 a.m., but prior to going get back on a time clock of earlier bedtime and rising time. You will not want to arrive at Maxwell IV in July and after 6 weeks at home going to bed at 2, waking up at 12 to get there with your body clock messed up. Granted day 2 your head will hit the pillow, but the problem will be your body is use to 10 hrs of sleep...ain't going to happen!
Finally, don't fret over this. The AFROTC boards viewed highly and selected you in a very competitive yr. They will break you there, but they will also re-build you. You will do just fine, you and your det have trained for this all yr., trust that.
Good luck. Remember when you are thinking to yourself this stinks, a few weeks later when you are back at school with the cadre you all will laugh in the ROTC lounge about the stories. Funny thing about memories the view of the moment changes with time.