Tips for Working Horses Alone

I have been working horses since I was 12 years old. Most of the time I work horses by myself, and (knock on wood) have not gotten into trouble. I do keep my cell phone in my pocket all the time, but this does not help if you are knocked out cold. Last year in my community, a woman was seriously injured at a barn. She was alone, knocked unconscious, and was at the mercy of people finding her, which was several hours after her accident. In trauma, time is of the essence. This got me thinking about my own safety practices. For all of you who work horses alone, what things do you try to assure safety? Have you been in situations where you were alone, something happened, and you were screwed until help arrived?