The 75 Hard Challenge can help strengthen the immune system by promoting habits that support overall health and well-being. The program's structure encourages participants to engage in daily practices that enhance immune function, such as regular exercise, proper nutrition, and adequate hydration. By following a healthy lifestyle for 75 days, participants can improve their body's ability to fight off illness and maintain optimal health. The challenge's emphasis on discipline and consistency helps individuals make lasting changes that support their immune system. The daily reading habit can include books on immune health, providing valuable insights into maintaining a strong and resilient immune system.