I think several of the fruits of the Spirit are missing in our current culture, but the one that really seems evident in America today is Self-Control. I once heard that Love and Self-Control are the two major bookends of fruits that hold the rest in there. I see it missing when I watch a show about hoarders, or The Biggest Loser, or 16 and Pregnant. People want to buy what they want, eat whatever they want and sleep with whomever they want with no consequences. The problem...there are consequences and they are serious.
So how do you teach your kids self-control? First of all, you talk about it and identify when your kids are out of balance. You praise them when you see them using self-control. But of course, the most powerful teacher is when you model it in front of them. When you are disciplined to exercise when you don't feel like it. When you tell them why you are fasting. When you explain that you have to wait on a purchase because it isn't in the budget. When you stop yelling at them and keep your emotions in check.
I'm still getting there. My husband was out of town for two weeks and I lost my temper a couple times. That is when you get to teach another great lesson...forgiveness.