A very popular pastime for Germans young and old is to join a Volksmarching club. Each weekend, beginning in the spring and lasting through the end of fall, cities all over German host Volksmarches--usually about 5-10K in length. People travel from near and far to participate. It's all about camaraderie and having fun--while enjoying the fresh air with a long walk in a beautiful location.
It's also then that people receive their small metal badges--which are later carefully nailed to their walking sticks. Each city will have its own.