Vaccinations exist for the flu and the chicken pox
Answer: Internal influences may mean health hormones, as hormones are a key structure in how we function. An external influence could be sleep, as humans need sleep as a way to recharge, or diets as they have an effect on both hormones and physical durability
Answer:
Maybe Jumping Jack's, Lunges, Planks and Squats. To avoid injuries, before and after every workout you should warm up and cool down
