Retirement just kind of happens. If we live long enough, we'll eventually reach a point where we either leave our careers, opt for another, less intense work life, or finish working for a living altogether. There was a time when companies included pension plans in their compensation packages and employees could look forward to receiving a percentage of their salaries to live on for the rest of their lives. Social Security benefits used to be enough to offset the cost of living, so that a person could retire based on Social Security income alone. In the 21st century, neither of these hold true any longer.