Don’t have children.
It may be too late for some of you, but if you don’t have an innate desire to have children, then don’t. I know that your parents probably want grandchildren and that there is subtle pressure to reproduce from all corners. However, raising children is hard work and if you aren’t into it, your child is the one that suffers. From a “living within your means” standpoint, the less people you have to spread your money around to, the easier it is to live within your means. Plus, you know how hard it is to resist when you yourself want “fabulous tchotka that will make your life so much better”? Imagine if it was your cute 8 year-old offspring making the argument. Based on the number of Heeleys at the school I work at, I’m guessing that saying “no” to the fruit of your loins is even harder than saying to yourself.