Some people seem to have a sunny disposition, while others always focus on the darker side of things. Are they just born that way? Yes, to some degree, says Jason Selk, mental coach and author of Executive Toughness. But it may surprise you to learn that you can mentally train yourself to change your outlook on life toward the more upbeat.

"We're born with a range of potential for optimism or mental toughness," Selk says. "Human beings are made up of thoughts, feelings and behaviors, and thoughts control both how we feel and how we behave. We aren't prisoners of those thoughts. We can choose the way we think, and in so doing, choose our entire life experience."

Optimists lead better, longer lives. During the 1960s, Martin Seligman used personality questionnaires to sort Mayo Clinic patients into optimists and pessimists. When he followed up with those patients 30 years later, the optimists were 19% likelier to still be alive. "If you're an optimist, you'll live longer than if you were a pessimist," Selk says. "And you'll be healthier, happier, and more successful during those years."

Is that enough to convince you that training yourself for optimism is well worth the effort? If so, here's how to get started:

1. Switch your thinking from problem to solution.

Selk notes that human nature is to focus our attention on problems and dangers, probably a leftover survival mechanism from our past as prey for wild animals. So it's important to make a conscious choice to switch. "Any time you catch yourself focusing on a problem or self-doubt, ask yourself: 'What is the one thing I can do differently that could make this situation better?'" Selk advises.

That will get your mind focused on solving problems rather than worrying about them, and give you more confidence and a better chance at success. Try to make this switch within 60 seconds of having a problem-focused thought.

2. Give yourself a mental coach.

"Many of us feel more confident and perform better when someone is cheering us on," Selk notes. "Yet being a high performer requires that you watch, evaluate, and are accountable to yourself."

The solution, he says, is to mentally conjure up someone who has served as an inspiration, mentor, and role model. If you're faced with a daunting task, ask yourself how this person would advise you, or handle the challenge himself or herself. "Ask yourself: 'What would so-and-so do if she had two reports and only 24 hours to complete them both?'" Selk says.

3. Take 30 seconds each day to visualize success.

"Set an alert on your calendar to remind yourself to replay this self-image video daily," Selk advises. "This simple mental training exercise dramatically increases the likelihood you will achieve your win, and it will improve your mood."

To be most effective, your mental video should be as specific as possible, with details as to where you are and what you're doing in this successful future, he adds. "That will elevate a vague life plan into a true vision that you can use to transform the way you think about yourself and your future."

4. Give yourself pats on the back.

I actually reach back and physically give myself a pat when I've accomplished something. You don't have to be that literal but however you do it, "Develop the habit of recognizing your 'done wells,'" Selk says.

Don't wait till you've finally finished that huge project or made that successful presentation. Instead, recognize incremental successes and accomplishments. "Take a few seconds per day to ask, 'What have I done well today?'" Selk says. "This simple gesture reinforces optimism on a daily basis. The answers inevitably add up to help you develop self-confidence, which is extremely important for high-level performance."