I'm 42 and have been putting 12% of my paycheck into a 401(k) since my first job, but I recently realized I have no idea what my actual retirement number should be. Calculators online give me anywhere from $800,000 to $2.5 million depending on assumptions like inflation and health care costs, which feels like a useless range. A friend who's a financial advisor says the 4% rule is outdated, but another friend insists it's still the best starting point. Do you think anyone can really predict their retirement needs with any accuracy, or is it all just a guess we're supposed to make peace with?