"If you could start saving maybe 10 percent in your 20s for retirement, by your 30s you might have to save 15 or 20 percent, by your 40s you might have to save 20-25 percent. Once you're in your 50s you'd have to save 40 percent of your income to match what you would have gotten if you'd saved just 10 percent starting in your 20s.""
-Liz Weston, personal finance columnist