Over the years, just two emotions account for most of the mistakes investors will make in the financial markets. Succumbing to either one of them will have a deep and long-lasting impact on your ability to retire comfortably.

In my business, there is often a joke that you know when the markets are peaking out on the upside when clients call and want to become more aggressive. The flip side of that is when the markets are tanking and clients demand at the very bottom that you sell everything and put them into cash. The number of phone calls is directly related to the fear or greed that investors are feeling in any given period.

Guess what—the number of phone calls and emails are accelerating. It should come as no surprise that 100% of the calls are investors who want to “chase” the market. Greed is now taking over and I can see it throughout the stock markets.

It is part of my job to discourage these emotional requests. I’ve talked quite a number of investors out of making decisions based on these twin emotions. You really can’t blame investors, however. Most humans have the natural impulse to gather as much wealth as possible in the shortest amount of time. This goes double for those of us who are close to retirement age and feel we don’t have enough money to manage our retirement.

Investors also suffer from the “herd” effect. If your friends or associates are making more money in the markets than you are, well, that just makes those horns of greed and envy sprout from your forehead. On the other hand, when you are standing around the water cooler, as stocks are in free-fall, and your buddy says he went to cash in his 401(K), the tendency is for you to emulate his actions.

Everyone from Warren Buffet to former Fed Chairman Alan Greenspan have warned investors over  “irrational exuberance” throughout  the last two decades, but many investors still allow their emotional impulses to overwhelm their long-term investment game plan.

Above all, try and avoid getting swept up in whatever the dominant market sentiment of the day happens to be. In today’s market, it is all about the “Trump Rally.” Although the president-elect won’t even be sworn in until January, the markets are discounting massive corporate and individual tax cuts, a $1-2 trillion infrastructure program, and the removal of mountains of rules and regulations that have built up over the last fifty years.

In short, the markets are priced to perfection, which assumes that all of the above will fly through Congress and be implemented into law within the first half of 2017. Remember too, that Mr. Trump has certainly not indicated a timetable or even how all of the above would be implemented. At most, he has appointed some members of his cabinet, but greedy investors refuse to wait and see.

Now that does not mean you should simply buy and hold. In investing, you need to be flexible. As the facts change, so should your investment strategy. It was clear to me, for example, back in 2008 that things had gone drastically wrong in the mortgage markets. I advised my clients early to sell everything, but facts, not fear, were the driver of my decision.

So if you believe that a case can be made to become more aggressive (based on the facts as revealed in the coming days of a Trump Administration), then by all means change your investment stance. But do so on a pullback because, as sure as the sun rises and sets, there will be a chance to buy this market at a more reasonable price.