If you have been worrying about the possibility of a recession, it’s time to let it go – not because we aren’t going to have a recession, but because we are. Worrying about whether a recession might happen is a bit like worrying about the possibility of a severe thunderstorm; we may not know exactly when, but it is going to happen at some point. And then it will happen again sometime later.

Instead of dwelling over all the horrible things that might result from a thunderstorm, we ought to focus on making sure our roof doesn’t leak and there isn’t a dead tree that might get blown onto our house.

The next president will likely face both a recession and a meaningful decline in the stock market – no matter who it is. The stock market has declined more than 20% roughly once every four years, so it is going to happen.

And before you start thinking (worrying?) that you can avoid the 20% drops, know that the penalty for being wrong is severe. In each of the three years that the stock market doesn’t experience a 20% decline, the average return is about 14%.

Worry is an emotion, and emotion is seldom a useful tool for decision-making. In high-stress, fight-or-flight situations, people often describe their successful actions by saying, “I didn’t have time to be scared.”

There is a difference between planning and worrying. Often, a lack of planning can even be a cause of worry.

Dr. Kerry Ressler, professor of psychiatry at Harvard Medical School,

explains that when we engage the amygdala portion of our brain with worrying, it diverts energy from the parts of our brain needed to perform higher-order tasks. He says that chronic worry and stress might actually rewire our brains, reducing activity in the areas of our brain that handle critical tasks, such as the prefrontal cortex.

That is, the more we worry, the less proficient we become at completing difficult mental tasks and making difficult decisions.

In my almost 40 years of observing investors, I’ve noticed that the people who worry most about their investments are those without a well-defined plan or strategy. If you make an investment decision (or any decision) based on emotion, it is difficult to know how to respond when something unexpected happens. And the real risks lie in the things that are unexpected, not in those we know are inevitable.

My advice: if you can’t control it or affect it, don’t worry about it. If it is inevitable, don’t worry about it. About the only useful purpose that worry has served in my life has been as an emotionally draining alarm telling me when I have left something undone.

David Moon is president of Moon Capital Management. A version of this piece originally appeared in the USA TODAY NETWORK.