If you're not exercising this emotional muscle, you're probably setting yourself up for failure.

I'm utterly convinced that the key to lifelong success is the regular exercise of a single emotional muscle: gratitude.

People who approach life with a sense of gratitude are constantly aware of what's wonderful in their life. Because they enjoy the fruits of their successes, they seek out more success. And when things don't go as planned, people who are grateful can put failure into perspective.

By contrast, people who lack gratitude are never truly happy. If they succeed at a task, they don't enjoy it. For them, a string of successes is like trying to fill a bucket with a huge leak in the bottom. And failure invariably makes them bitter, angry, and discouraged.

Therefore, if you want to be successful, you need to feel more gratitude. Fortunately, gratitude, like most emotions, is like a muscle: The more you use it, the stronger and more resilient it becomes.

Practice Nightly

The best time to exercise gratitude is just before bed. Take out your tablet (electronic or otherwise) and record the events of the day that created positive emotions, either in you or in those around you.

Did you help somebody solve a problem? Write it down. Did you connect with a colleague or friend? Write it down. Did you make somebody smile? Write it down.

What you're doing is "programming your brain" to view your day more positively. You're throwing mental focus on what worked well, and shrugging off what didn't. As a result, you'll sleep better, and you'll wake up more refreshed.

Reprogramming Your Brain

More important, you're also programming your brain to notice even more reasons to feel gratitude. You'll quickly discover that even a "bad day" is full of moments that are worthy of gratitude. Success becomes sweeter; failure, less sour.

The more regularly you practice this exercise, the stronger its effects.

Over time, your "gratitude muscle" will become so strong that you'll attract more success into your life, not to mention greater numbers of successful (i.e., grateful) people. You'll also find yourself thanking people more often. That's good for you and for them, too.

This method works. If you don't believe me, try it for at least a week. You'll be amazed at what a huge difference it makes.