You have to be in relatively good shape to join the Guard. There are weight restrictions (based on your height), and you have to be able to complete a simple physical fitness test. Your recruiter can tell you if you meet the requirements and give you tips on how to get there if you don't.
The Armed Services Vocational Aptitude Battery (ASVAB) tests your ability to perform certain jobs. Your scores on the test will determine which jobs you qualify for.
The ASVAB has sections on topics like "Automotive and Shop Information," "Mathematics Knowledge" and "Paragraph Comprehension."
