Charles Schwab's chief investment strategist Liz Ann Sonders has a message for investors: buy low and sell high.

It sounds simple, but investors don't always follow the ultimate Wall Street adage

"You have to try to take the heart out of the game and just use your head," she said, referring to the tendency for people to look for bargains at the supermarket, but not necessarily in the stock market.

According to Sonders, rebalancing one's portfolio allows for this strategy of buying low and selling high to take place naturally. 

"Your portfolio is going to tell you when it's time to do something," Sonders said. "You don't have to worry about what my views are on the market or any other pundit that's out there."