2. Volatility is not the enemy.
Stocks provide you with the best chance of outpacing inflation and reaching your goals. But the cost of higher expected returns is higher expected volatility.
The wonderful thing about return volatility is that it works in favor of long-term investors. High volatility in the short run provides rebalancing opportunities that allow you to buy low and sell high. Meanwhile, stock market returns over longer time horizons tend to be less volatile.
3. You should consider rebalancing, but don't ignore bonds just because rates are expected to rise.
If you haven't rebalanced in a while, then now is probably as good a time as any.
Read MoreInvestors bailing on U.S. equities in greater numbers
Rebalancing from stocks into bonds may be a difficult pill to swallow with the seemingly imminent tightening of U.S. monetary policy, but remember that rising interest rates are actually a good thing for long-term bond investors. Bond prices do go down as yields rise, and in a rising interest-rate environment, that's a concern front and center with investors. Keep these three principles in mind to try to see through the rising-rate hysteria when it comes to the bond market:
- The primary purpose of bonds are to decrease the volatility of the portfolio.
- The worst bond markets are far less severe than the worst stock markets.
- The ability to reinvest interest and principal payments at higher yields helps offset losses and provides higher returns over time. This applies to both individual bonds and bond funds.
4. Diversification doesn't just matter over a lifetime; history suggests it might be particularly fruitful right now.
An allocation to global stocks as part of a diversified portfolio has historically provided some modest benefit to long-term investors via a small improvement in risk-adjusted returns and superior performance during down markets in the U.S.
Still not buying it?
Perhaps you ought to consider the tendency of global stocks to outperform in the five years following an annual loss. Global equities recorded a 3.64 percent loss in 2014, which history suggests could be a precursor to outperformance in the next five years.
Here's the history on that: