Every year I do some back-of-the-envelope investment planning to set some goalposts. It’s a useful process to take stock of where you are, where you’ve been and where you’re going. I take our current net worth and savings rate. Then I make some assumptions about future savings rates, income and return expectations. Those return expectations exist in a range because it’s impossible to predict the future. Then I model all of these numbers going out 5, 10, 15 and 20 years.