The same parts of the human mind that allow people to imagine the future and anticipate happy events are also the ones that allow for worrying and imagining worst-case scenarios. 
While these can be helpful in moderate doses, too much worrying can promote anxiety and despair.

The dark side of anticipation

The human brain can concentrate only on a couple things at a time. So, when we have positive anticipatory things in our mind, there is less room for negative thoughts.

Anticipation can reduce stress

“Having things to look forward to is a major coping strategy. It helps us recover and adapt to stressors.”

Especially in uncertain times, being too wrapped up in future plans and pleasures does not always bring happiness.
<ul>
<li>If you find that the thoughts you’re having about the future are not productive, anchoring yourself in the moment can be a good thing.</li>
<li> Inject life with small, short-term sources of happy anticipation. You can still anticipate positive events, but you may have to scale it back ( for example, plan a cocktail-hour call with a good friend in the following weekend).</li>
</ul>

Too wrapped up in future plans

This ability is what separates us from most animals.
Our frontal lobe is the one that helps us anticipate and make decisions, and that certainly is a higher-level function. Opposed to this is the emotional part of the brain (the “more primitive” lower brain) which at times can clash with and overwhelm the deliberative brain.

The brain’s ability to look ahead

Much of life's bliss is enveloped in expectation, in looking forward to something new. But as soon as that new something happens, we often turn our thoughts ahead to the next expected joy or novelty.

The sources of human happiness

When people can no longer look forward to vacations, weddings, or other happy events, they often struggle psychologically. Experts share how to regain that feeling during a pandemic.

The dark side of anticipation

Similar ideas to The dark side of anticipation

5. Control of Emotions

Anti-goals and anticipating the worst

The Dark Side Of Mind Wondering