I Timothy 6:8-
And having food and raiment let us be therewith content.
In our world of overabundance, many are starting to wonder, what is really necessary? How can we scale back and what is truly a need? This tiny verse in I Timothy is the answer. Food, clothing and shelter. (The word raiment here can mean both clothing and more broadly, a covering or shelter.) You can do without everything else. I think you know that this doesn't mean God promises us we can have sushi, Gucci and a mansion. It may mean for some of us, tuna fish, thrift stores and a tiny apartment. Others may have big things, but having basic needs met, should satisfy us. We have enough. It may not be your ideal and that's okay. But you have the essentials.
When training our children to be content, there are two things to remember. One is that it is caught, not taught. If they see you content with where you are, i.e. not complaining and worrying about how little you have and wanting what you don't have, then they are much more likely to be content themselves.
Second, there will more likely than not be a season (or two) where food, clothing and shelter is all you get. Needs are met, but no room for wants. You can't start talking about contentment when you are down. It has to be your attitude and talked about before so when the time comes, they know the expectation.
Prepare them for what may come. And show them that no matter what, God is providing for them too!