As I mentioned elsewhere: hydrate, hydrate, hydrate!, and remember to replenish electrolytes with fluids like Gatorade.
Nutrition is an important part of my search strategy because I have an odd eating habit. I only eat until I am not hungry. I never eat until I am full. I hate the drowsy feeling of being to real full. The moment I no longer feel hunger, I stop, even if I have only taken 2-3 bites of a sandwich. I will eat more when I feel hungry again, usually in about an hour. As a result, I eat 10-12 times a day in these small portions. This keeps me light on my feet and never bogged down. My family say I graze.
It may be beneficial for you always to carry some source of quick energy carbohydrate in the field especially if you have a physiology like mine. I weigh 150 pounds, and do not have a lot of body fat, so with my eating habit, I often run out of gas on a strenuous hike. I always pack protein bars and snacks, but I can still run out of energy. I can quickly use up the glucose in my blood and even deplete stored up glycogen. At that time I hit a wall, and feel dead tired. This concerned me at first, but I now know it is simply a blood sugar issue. To deal with this, I always carry a small bottle of honey in my backpack. Whenever I feel that tired heaviness, I gulp down two big mouthfuls of honey and a pint of water. I find a shady spot, lie down and check the time. Predictably within 15 minutes the heavy cloud of tiredness lifts and I’m good to go again. Listen to your body and be safe.