I always thought it would be charming to sing while hiking, but it reminds me too much of counting cadence to obscenities when I was in the army - and then the hike becomes a forced march to me. Most of my hikes are in rough terrain, and I think you have to keep up an even pace to sing while hiking. So, I enjoy quiet conversation instead. One time when I was on a nice, quiet hike in the Sierras, I heard what sounded like a troop of soldiers marching and counting cadence:
Hail Mary, full of grace, the Lord is with thee....
I'm Catholic, but I thought that was obscee.
I still would like to have a nice singing/hiking experience someday. Maybe I can hike the Loire or the Midlands and do that.