I graduated in 1999 and started investing right away. I have been through the first crash as well as 2002, and the most recent lengthy one in 2009. I suppose since I was able to put so little away when I first graduated that this was no big deal to me, and as the market crashes kept coming, I kept working and put more and more away. With the recent rallies, up 30% this year for example, I am not sure why this is a big conern.
If, and only if, the market is in a sharp decline when you are near retirement, simply work a few more years until it recovers, then quit. Cut back your spending in the meantime so you can save more. I have never met one person in my life who couldn't cut back their spending somewhere, usually in significant ways. Monthly recurring bills are the worst, because people pay these things without analyzing them.