"The purpose of a retirement plan is to replace income in retirement. If you're still thinking about your retirement plan in terms of accumulated assets you might be more likely to have a negative reaction to market declines.... However, if you're thinking about your retirement plan in terms of the monthly income you'll receive in retirement, then market corrections are going to seem less impactful. The effect of even a large market move on your monthly paycheck in retirement is going to seem insignificant if you're planning for the long term."