I am a Fitness Instructor in NC. I have taught some of the BLET fitness blocks. Generally if you don't quit or give up (wimp out) you will make it. The intensity of the PT varies from school to school. Where I teach at we are usually pretty hard on the newbies and usually one or two will quit on the first day. The PT is not hard though. We start with a warm up and stretches, then do sets of 10 calisthenics, then usually do some sort of cardio, and then a cool down. As the weeks go by we will increase the sets and some days will do only a few calisthenics and a longer run. Like I said the intensity will depend on the school you attend. The main thing is don't give up mentally.
The longest I ever ran a BLET class was about five miles and that was with the "A" group near the end of the class.
NC Fitness Instructor