I don't know if you have the same problem with the EarPods that Apple ships with the iPhone 5, but I find that a lot of times the friction of the cable on my shirt has a tendency to pull the pods out of my ears. It's annoying, especially when I'm in the middle of a phone call and the right side of the cable -- the one with the mic -- decides to flop down on the front of my shirt. Well, there's a product to help out with that problem. Klingg (US$19.95) is a tiny and very useful earphone magnet that holds the main cable in place on your clothing, keeping the EarPods from popping out.
Klingg comes in a variety of color combinations to please just about anyone and is made in two pieces, each with a very powerful magnet inside of it. You put the main cable of your headphones into a slot on the front of the Klingg, then pull the rear half off of it. Put that rear piece under a piece of clothing, put the piece holding the headphones on the front, and now you have a strong, stable base holding your headphones in place.
When you're walking around and have the EarPods out of your ears, you don't have to put up with the pods banging into your body because they can be auto-magnetically attached to the Klingg.
Having part of my heritage from Italy, I have a hard time keeping my hands still when I talk, so my EarPods used to fall out a lot. Since I started using the Klingg, that doesn't happen very often at all. Klingg is a surprisingly useful product that solves a problem I didn't really know I had.