Unbearable Summer or Winter: people often get sick because of quick changes in temperature... bacteria thrives on quick changes in temperature.
Drink Plenty of Water: water not only hydrate the body... but also flush toxins and bacteria away. Add a slice of lemon/lime to water when ever possible... the acidity kills most common bacterias.
Healthy Food/Non Fatty: Fatty foods carries a lot of toxins, such as bacteria. Fat stores hormones injectected by food industries to increase productivity. Natural chicken takes 3 months to mature.... hormones injected chickens takes 5 weeks.
Light clothing: it let your body regulate temperature much more easily without additional heating during summertime.
Take a shower: Water wash away bacteria and toxins... often twice a day is more than enough.
RE: How to stay healthy in summer