On hiking poles 

When I walked across country in 08, I didn't think of using hiking poles until fellow cross-country walker Jodi Beth Harrington recommended them. I purchased a set of aluminum (?) telescoping sticks in Virginia, lost them in Connecticut, and borrowed a pair from Couchsurfers Matt and Lauren which carried me into Boston. It took me about one day to get used to walking with them, but once I was accustomed to coordinating my arms and hands with my feet and legs, the poles really helped to both establish rhythm and take the strain off the knees and hips. The only downside (especially in winter) was to do anything - take a photo, hand someone the book, send a text message, the poles I had to put the poles down, take off my mitts, take out the phone or book, then, when I was ready to move on, put the phone or book back, put on my mitts, pick up the poles, etc. The poles were helpful but not convenient.
Anyways, during this walk I chose to walk with poles again, and used one pair from Boston to DC. After a month of pounding pavement they were in pretty rough shape. One pole couldn't collapse like it should, and since I couldn't fly with them extended, I asked Kate to drop them in her trash for me. Before she did, though, I took this photo of the pole tip. When they were new, the rubber covering extended to the tip of my thumb. After 450 miles the rubber had worn down to this stub. Even the metal which made up the pole itself was filing down. Had I kept walking eventually I would have needed longer arms - hahaha.
But seriously, if 450 miles of constant thudding against concrete did this to rubber and metal, I wonder what 4700 miles did to my ankles, knees, hips and back.