The first American astronauts heading for the moon had a strict mission: Land two men on the lunar surface and return them safely to Earth.

While they were on the moon, they took samples, conducted experiments and took photographs. They did what their mission said, and they made history.

Just like Neil Armstrong needed a clear mission to achieve his objective, businesses do too. Having a mission statement helps entrepreneurs focus on the essence of their business's goals and the philosophies underlying them. It protects you from yourself.

Related: Five Reasons Why Your Mission Statement Probably Stinks

You may not think you need protection. But come on, you’re an entrepreneur! Your brain rarely shuts off. You’re constantly manufacturing new ideas and dreaming up new plans. If you acted on every single notion, you’d never get anything done. A mission statement is a safeguard against you going completely off the rails chasing down some every new thought and losing focus of what you’re trying to achieve. The mission statement makes you stick to that plan that was so clear when you first began.

Over the years I’ve crafted many mission statements -- some worked and some that were just duds. I look back at the ones that didn't work and I can see their flaws -- they were over-reaching, too wordy or too narrow. The best ones were short, succinct and to the point. For example, my mission for my latest endeavor Patriot Software is "To help small business owners with easy and affordable software." It works because it’s reasonable, memorable and achievable.

Related: Change the Rules: 5 Ways to Bring Mission Into Your Business

When you create a mission statement, you are telling yourself (and the world) that this is what my business is going to be about -- this is what I’m going to achieve. Plus, if you are trying to raise capital, you better know your mission statement backwards and forwards. Otherwise, investors may feel you aren't focused enough.

But once you create it, don’t just check it off your to-do list and file it away -- put it to work. Plaster it somewhere that you and your employees will constantly see it. This will help you retain it, believe it and start making it happen. Make a practice of periodically reviewing the mission statement to make sure you’re still on track. If you veer off course, your mission statement will jump right out and embarrass you back into compliance.

Related: Richard Branson on Crafting Your Mission Statement