If you are considering teaching in "the developing world" you should be sure about your motives before you go.
If you are thinking about it because "it's what good people do" or some such thing, I would say forget it. Doing something because it's "the right thing to do" is not a recipe for happiness. Don't do it out of altruism.
That is not to say that helping people who can really use help is bad. But do it because you will feel good about yourself and find it personally rewarding.
If you really think it will be rewarding, then go have a careful look and see if it really might be for you. For example, scope out what your living conditions might be. Hot and cold running malaria? Fresh water on alternate Tuesdays? Tarantulas for house pets? Is there an internet connection in the same weather zone? Figure out what the minimum commitment time might be. Figure out what language barriers there might be. Figure out what "political" issues there might be. Is the place you are considering equipped with a civil war? Do the locals have a hate-on for persons who look like (act like, eat like, believe like) you?
If you can accept all of that (shopping will be unlikely) and still look forward to it, then go for it.