If you've ever gone through a period of depression as you battled the ups and downs of entrepreneurship, you are not alone.

Many entrepreneurs go through short periods of depression (meaning less than a month), especially after selling a company, experiencing failure and rejection, or facing a big change in the business. And with so many cultural myths about who entrepreneurs are or should be, sometimes the fear that you are falling short is enough to bring you down.

Depression breeds feelings of self-doubt, regret, worry and fear that can hold you back from achieving your goals if you let them get out of hand. But, short periods of depression are extremely common, and can even be useful clues that something needs to change.

"Negative moods are really just signals that something is going on that you should be paying attention to," says Julie Hergenrather, a clinical psychologist and executive director of the Beck Institute for Cognitive Behavioral Therapy. "They're not personality flaws."

Related: How to Stay Calm in a Crisis

By noticing negative moods, you gain the opportunity to deal with those feelings proactively. "Adopt an attitude of curiosity," says Hergenrather, as opposed to avoidance or judgment.

Try these four steps to notice and break out of a short depression:

1. Look for shifts in your mood.
Depression rarely starts with a fully realized thought about what's going on and why -- that would be too easy. It starts with a bad feeling that we often push aside.

For example, you might feel your stomach drop, your heart rate accelerate, your energy wane, or your body tense in reaction to a business decision or interaction. "That's a good moment to stop and ask yourself, what am I thinking right now," says Hergenrather. Your physical reaction is simply a way to alert you to a possible problem.

2. Notice which thoughts are getting you down.
During times of depression, our thoughts have a negative or fatalistic outlook. Thoughts like "I'm a failure" or "I'll never get ahead" are common. Often, these thoughts are so automatic we don't even notice them, but they keep us locked in a negative spiral.

To uncover your own automatic thoughts, explain them aloud or write them down. Dig deeper by asking yourself, "How do I feel about that?" or “What do I think will happen?" Look for the thoughts that evoke a genuine emotional reaction. "The thoughts that are really causing the problem will pack the most emotional punch," says Hergenrather. "That's how you know you’re at the core."

3. Ask yourself if those thoughts are completely true.
Automatic thoughts associated with depression have one fatal flaw – they're typically untrue. They feel true, but that doesn't mean they are. So once you know which thoughts are causing you trouble, challenge them.

Ask yourself: Can I think of other times when this thought wasn't 100 percent true? Is there another side to this story? What would a trusted advisor say to me? Is there a problem here that could be solved? Look for any evidence to suggest your automatic thought might be wrong or incomplete. "Challenge yourself to think about the situation more accurately," says Hergenrather.

In some situations, a thought may be true (i.e. my company failed), but the meaning you attach to it (i.e. I will never succeed) is not objectively true. In those cases, challenge the meaning.

Related: Train Your Brain to Overcome Fear

4. Rewrite the story of your situation.
After you challenge your automatic thoughts, summarize what you've discovered. Just say it back to yourself in a couple of sentences so you can hear it aloud. "You won't change the situation, but you'll have a more balanced perspective," says Hergenrather.

If you notice that the same automatic thoughts recur often, try writing the balanced perspective on a notecard and taking it out whenever you need a reminder. The quicker you can nip negative thoughts in the bud, the less power they’ll have to get you down.

Important Note: If you experience a depression that lasts longer than three weeks, persists despite your best efforts to relieve it, or is associated with any thoughts of self-harm, please see a professional therapist in your area. Depression is treatable -- you just have to reach out for help.