1. Take Cold Showers
For the last 5,000 years, yoga practitioners in the East have been recommending cold-water showers to boost immunity. Research also shows that cooler showers can help increase your white blood cell count (which can help zap illness in your body) and increase circulation.

2. Eat a Plant-Based Diet
Eliminating the carcinogens and saturated fats from meat -- or even just cutting back -- is very beneficial. Plants offer all the nutritional and phytochemicals you need, plus a plant-based diet arrests and reverses heart disease. Firefighter Rip Esselstyn, who is featured in the book, inspired his whole firehouse in Austin, Texas, to become vegan. They all increased their “good” HDL (high-density lipoprotein) cholesterol levels and decreased their “bad” LDL (low-density lipoprotein) levels.

Get Vegan Recipes

3. Eat Dirt
This doesn't mean eat it by the spoonful! But if a piece of food falls on the floor (assuming it’s not pudding), the two-second rule applies, and it’s OK to eat it. This secret has to do with a theory called the hygiene hypothesis, which explains the increase in immune system diseases like food allergies, hay fever, and eczema in developed countries. Basically, the theory states that we are too clean, so our immune systems never get the chance to develop properly. The immune system is like a locked and loaded army, always ready to go. But if it has nothing to do, it turns on itself.

Of course, you should continue to wash your hands if it’s flu season, and immunize your children. But let them be kids. Allow them to go outside and have contact with Mother Nature. A study in the Philippines revealed that kids who played in a sandbox actually got sick less often.

4. Stretching
This secret was discovered by Dr. Robert Fulford, who was internationally famous for his ability to heal people who conventional doctors had given up on. He was hardly ever ill throughout his life, and claimed that one of the reasons for this was a set of stretching exercises he had developed. Fulford believed that the body wanted to be healthy, and that if it got tense, it would suppress its own systems, leading to sickness.

Try These Stretching Exercises

5. Eat Raw Garlic
Research shows that raw garlic has powerful antimicrobial, antioxidant, and antibiotic properties. But you need to eat it raw in order receive the most health benefits. Allicin, a powerful medicinal compound found in the plant, is only released when mixed with saliva. Feel a cold coming on? Chew a clove of garlic a few times a day -- followed by a sprig of parsley for fresh breath.