Dehydration and lack of food are enemies that can strike at any time because once you get a call, you never know when you ll get your next meal or even drink of water. A bottle of water and a couple of balance bars in your kit can make all the difference when you get stuck on that long call. Signs of dehydration include headaches, lethargy, decreased urine output and an increased pulse rate. Low blood-sugar and lack of food can make you jittery and very tired. Both states decrease your performance, judgment and survival potential.