If you are seriously considering a career in the US military, you should take the military version of the entrance exam. This is known as the Armed Forces Professional Skills Battery, or ASVAB for short. Of course, you need a strict training plan and for that, you can get the latest ASVAB test study guide from https://www.andysasvabclass.com/.
ASVAB was created to test you on the material you studied during your high school education. Some students may remember different topics, but most students tend to forget information when sufficient time has passed.
If you only have one month to work on your ASVAB, you need to actually get it done, create a rigorous curriculum, and then study like there's no tomorrow. Remember, you joined the military, not the intelligence girl.
This means that you need to be prepared for mental and physical stress. So if you have reached your limit, you are on the right track. Start your learning process by taking a baseline or practicing ASVAB. This way, you can see not only where you are, but also which areas need improvement the most.
Take your practice exam in exam-like conditions. This means a quiet room, perhaps in a library, without distraction or distraction. There was no cell phone and certainly no calculator.
Take a mental break after the test. Use this time to research specific industry requirements and evaluate your job. Now your test scores. See what you are missing in each section and list general topics and thematic material.