I suffered from heat exhaustion last summer. What can I do this summer?

Stay hydrated. Drink plenty of water when it is hot and you are going to engage in strenuous activity. We all should drink at least two quarts per day not exercising or being in the heat. You will need more if excersing, especially in the heat. First axiom of exercising and hydration. Drink before you feel thirsty. Once deydrated, the GI tract cannot absorb water fast enough!