Survival, in combat situations as well as off the battlefield involves having the right gear, the knowledge to use it, but also the level of preparation you've given your body. The most elemental level of self-preservation lies in your body's capacity for survival. With balancing your diet and physical fitness, you can ensure your ability to respond quickly when you most need it. In previous articles, I've discussed how staying hydrated and eating right can impact how efficient of a machine it can become, but operating smoothly is only half of physical fitness. The other half lies in body strength, which can only be developed through exercise. In the lectures I've attended as a biology student, and in the material I studied to tutor anatomy and physiology, I've learned about the muscular system and how it functions, on the molecular and visible levels. As a runner, though, I've been able to apply this knowledge in a practical fashion to improve my performance as an athlete. I'll summarize some of the key points I've learned through that experience and education as it relates to overall physical fitness in this article. Calories In = Calories Out Balancing your diet is an important part to staying healthy, but it has little impact on the strength of the body, except to provide the energy it needs to function. To continue to improving your level of physical fitness, you must also regularly exercise. When you have to march any measure of distance all geared up,