For the past few months I have been doing training walks. I have been using a free website called Plot-A-Route to not only plan my walks but to generate the gpx (GPS) file to load into my GPS map reader (more on this later). You can then share a link or print the map, to share with others so they can see your route. This route, shown below is a 9 mile walk I planned several weeks ago and was walking it when I realized my shoes were too small so I had to be picked up 8 miles into the walk.
I started with one app that just read the gpx file and I was using another app to track - both were free and I was learning to use them but then I found an app called A-GPS Tracker that not only did both had a nice feature where you can load a gpx and then tell it to alert you when you go "off track". This is good for when you are walking but not constantly looking at your phone; it is a rather large alarm!
Here is a sample text message I sent yesterday morning before my 9 mile walk.