While fooling around in my workshop the last two Saturday mornings, I found a show on public television called "Wealthtrack" hosted by Consuelo Mack, the two subjects were how to make your retirement funds last as long as you do, and general stock market investing, interviewing people. I enjoyed both shows, planning on trying to catch it on Saturday mornings the rest of the winter.
At the end of the last show, her point was that a person "No matter how tempting, avoid market timing" implying when the market tanks, don't loose faith and bail out. The hard part is knowing when to get back in, and people usually wait too long. So make sound investments, and leave them in there. She had two facts, which sounds pretty wild to me, but thought that I would pass them on to you, fwiw:
1) Being out of the U.S. Stock Market for the best 25 days, for the period of 1970-2015 (45 year period), reduced returns from + 1.910% to + 371%.
2) Being out the the U.S. Stock Market for just 2 quarters since 1900 reduced returns by + 66%.