I am not much of a TV watcher, and when I do tune in, I’m usually half-watching, half-working on something else. But sometimes you learn things from unexpected places, and it so happens that a recent Gatorade commercial grabbed my attention.

The ad shows some of the world’s best athletes, like Michael Jordan and Peyton Manning, remarking on their failures—Jordan’s inability to make his high school varsity team, Manning’s abysmal rookie season—and how those defeats redoubled their drive.

What a powerful message. Even Atlanta Falcons quarterback Matt Ryan makes an appearance, acknowledging his team’s mind-blowing, fourth-quarter Super Bowl fall to the Patriots in 2017 and implying that he, too, would grow from the experience.

This is the time of the year when we think about recharging, renewing and redefining ourselves. People this month will do anything, from joining a gym to embarking on a spiritual retreat.

“Whether you are 15 years old or 50, your outlook toward life is always under construction.”

These are worthy endeavors, but there’s a more life-altering change we can make in the mode of those superstar athletes. What each of them has done is adjust their attitudes. They see life through a positive lens, no matter what it throws their way. That optimism fuels them, focuses them, and allows them to put setbacks in perspective.

Attitude can be our best friend or worst enemy, the librarian of our past, the speaker of our present and the prophet of our future. In short, I believe attitude is the biggest determinant of our quality of life.

There are people who seem perpetually perky and whose good nature appears as innate as their eye color. But attitude is not a fixed state. Whether you are 15 years old or 50, your outlook toward life is always under construction. It’s never too late to change it. If your attitude is deflating you, here’s how to pump it up.

1. Evaluate your current attitude

This is the hardest step in the process. You need to detach from yourself and take a hard look at how you respond to situations.

• Identify your problem feelings. What attitudes make you feel most negative about yourself?
• Identify your problem behaviors. What actions create conflict between you and others?
• Identify your problem thinking. What thoughts cloud or control your mind?

2. Write a statement of purpose

If your biggest flaw is impatience with others, for example, vow to take a deep breath, listen to them more carefully and develop empathy—an ability to see situations through other people’s eyes. If your downfall is complaining, learn to smile, speak positive words, or if all else fails, silence yourself entirely.

3. Find new words

If you were trying to motivate other people, you’d pump them up, wouldn’t you? You’d offer words of support, encouragement and inspiration.

Do you do the same for yourself? So many people I’ve met—people with tremendous potential—shortchange themselves with a self-defeating internal voice. I can’t. I doubt. I don’t think. I don’t have the time. I’m afraid. I don’t believe.

This self-doubt darkens our attitudes, limits our success and casts a shadow over our lives. The fix is easy: Change the language. I can. I expect the best. I know. I’ll make the time. I am confident. I believe.

4. Rewire your thought patterns

Our feelings come from our thoughts. We can change them by changing our thought patterns.

It’s our thoughts, not our circumstances, that determine our happiness. Often, people are convinced they will be happy when they attain a certain goal. When they do, they are surprised and disappointed to discover that they don’t feel fulfilled. What they don’t realize is the act of filling one’s mind with good thoughts every day, regardless of what’s going on in their lives, will bring more overall satisfaction than the one-time high of a job well done.

5. Develop good habits.

An attitude is nothing more than a habit of thought. Habits aren’t instincts; they’re acquired actions. They don’t just happen; they are caused. Many people allow their habits to control them. That’s good if the habits enhance our quality of life. If not, well, life becomes cloudy indeed. You can change your habits. Here’s how:

•  List your bad habits.
•  Determine the root cause(s) behind them.
•  Determine a positive habit to replace a bad one.
•  Take action to develop that.
•  Act upon this new habit daily.
•  Reward yourself by noting one of the benefits of this new habit.

I see habit change as a process, so don’t dismay if you don’t see results overnight. The early stages will be the hardest. Those bad habits want to remain in control. In the middle stages, you’re on the proverbial fence, deciding whether to step fully onto the other side or tumble back into your old ways. In the late stage, you’ve successfully corrected a flaw and are enjoying the attitudinal shift that comes with it. But beware: Complacency is the enemy. Just ask anyone who has lost weight only to gain it back.

Back to that Gatorade commercial, where tennis great Serena Williams looks dead-on at the camera, steely-eyed. Her secret to victory was being “on the wrong side in the biggest upset of your sport,” a reference to her stunning fall in the 2015 U.S. Open to Roberta Vinci, an unseeded player from Italy.

Two years later, she became the only tennis player, man or woman, to win 23 singles Grand Slam titles in the Open era.

“I’ve had to learn to fight all my life—got to learn to keep smiling,” she says. “If you smile, things will work out.”