A bear market is a chance to reflect on how you really react under pressure. This probably won't be the last downturn you'll see, so now - when "risk" means something - is the time to set an investing strategy you can live with.
First do some cold calculations. Figure out how much you'll need to set aside in cash for spending goals over the next two years, such as taxes, a vacation or college tuition. Then look at the outlays you expect two to five years out. Invest that money safely - in bonds, not stocks.
Now plug your emotions into the equation. In theory, all the money you won't need for more than five years could go to stocks. But if this decline has already prompted you to flinch, possibly even to sell, you've learned you should have less of your long-term investments in equities.