Maintenance of Health: doing those things which will help keep the body functioning normally. Conserve body heat and stay dry in cold weather. Pace yourself in hot weather to avoid too strenuous activity and heavy perspiration. Avoid sunburn. Protect your eyes. Take care of your feet. Remove, kill, or repel insects and other pests. Keep hands, body, and clothing as clean as possible. Wash and dry your body daily, if possible. Do not put your fingers in your mouth unless you have no other choice. Clean your teeth by chewing a green tree branch or any grass stem except velvet grass (it can be poisonous). Purify drinking water with iodine tablets or by boiling at least 5 minutes. Boiling 20 minutes is safer. Avoid excess handling of food, and sterilize eating utensils in the fire. Treat new cuts, sores, or wounds on an immediate basis. As mentioned in the Field Care Chart, the roots of the curled dock (Fumex crispus) can be smashed and made into a salve that will fight infection. Yarrow (Achillea millefolium leaves can be ground to provide an external medication. And the inner bulb of the soap plant (Chlorogalum pomeridiamum), or the peeled root of the yucca (Yucca), can be used as a disinfectant soap for your body and clothes. Bury all waste at least 100 yards from any campsite. Select the downhill side if possible. Do not let wastes come in contact with food, cooking utensils, or clothing.  Wash hands after handling. You should know and be able to practice advanced first aid. See first aid related sections of this handbook.