I also ride alone most of the time...like the others said, bring emergency items, and let somebody know that you're out! Make sure your phone is attached to you, NOT the horse. Better safe than sorry. One suggestion if you don't want to ride alone all the time is to look for a trail riding club in your area and start asking questions. I was lucky to find a trail riding club in my area that is mostly made up of people conditioning for endurance/CTRs. We ride often, fast, and far. It's great to have this network of experts in the discipline who are so readily available to me!
A horse is the projection of peoples' views about themselves--strong, powerful, beautiful--and it has the capability of giving us escape from our mundane existance.