Final answer:
Walking, carrying things, and not eating can help Ned and other Navajos be good marines by improving physical fitness, mental endurance, and resilience.
Step-by-step explanation:
Walking, carrying things, and not eating are all practices that can help Ned and other Navajos be good marines. These actions can improve physical fitness, mental endurance, and resilience, which are important qualities for a marine..
Walking long distances can build endurance, carrying heavy loads can improve strength and stamina, and not eating for extended periods can train the body to operate on limited resources. These practices can help Ned and other Navajos excel in the physical challenges and demanding conditions that marines often face.