Expert reveals the six things mentally tough people have in common- and what you can tell yourself to be more successful

The secret to a successful and happy life is your ability to pull yourself up when life knocks you down. 

This is the theory proposed by Scott Mautz, a motivational speaker and former executive at Proctor and Gamble, who recently wrote a book saying the most successful people are the most mentally tough - those who can regulate emotions and control their thoughts and behaviors. 

Mr Mautz has spent three decades researching how leaders become mentally strong and determined they rely on six core factors: confidence, fortitude, boldness, decision-making, goal-focus and messaging.

Along with these factors, Mr Mautz said there are six phrases you can tell yourself everyday that will beef up your mental toughness - strengthening your subconscious like a weight lifter adding more reps each day - and prepare you to take on challenges.

Mentally tough people are united by six common factors- including confidence, fortitude, boldness, decision-making, goal-focused and messaging, Mr Mautz said

Mental toughness involves controlling your emotions, thoughts and behaviors in both positive and negative situations, Mr Mautz said

To start, if you're lacking in confidence, Mr Mautz wrote for CNBC that mentally tough people regularly use the phrase, 'I'm enough.'

Confidence can be elusive. Yet it's well established that people who report high levels of self-confidence tend to fare better, professionally and personally, than people without confidence, according to the Learning and Performance Institute. 

Confident people earned on average $28,000 more a year compared to less confident people, a 2008 study that included data from more than 12,000 men found. 

Instead of looking at differences or self-perceived weakness you may have, begin to believe that what makes you unique can actually fuel your success. 

Mr Mautz wrote: 'The only comparison you can make that’s actually relevant is between who you are today and who you were yesterday. The only question that’s truly important is whether or not you’re growing.' 

Fortitude, a measure of how well you're able to endure pain or adversity, is the second pillar of mentally tough leaders. The phrase Mr Mautz recommends using when presented with difficult situations in order to increase your fortitude is: 'What possibilities does this setback present'.

Reframing a setback as an opportunity can help trick your brain into working through a problem, even when it would be easier to accept defeat. 

For example, if you were reprimanded by your boss for missing a deadline, you might, naturally, feel upset. However, you can see conflicts of this sort as a potential to learn - learning what not to do in the future can improve your performance as a worker overall. 

Mentally tough people start from an understanding that they 'are enough'. Studies have shown people with a confident mindset earn more money than their less confident counterparts

Mental fortitude, being able to tolerate uncomfortable or upsetting situations, is a corner stone of mentally tough individuals

After resilience, Mr Mautz said mentally tough people have a bold streak. The phrase that most embodies this is, 'Am I letting myself dream big?'

If the answer to that question is no, then you might consider letting yourself think more ambitiously - setting career or personal goals for five or 10 years down the line. 

Believing you can achieve ambitious goals is the crucial first step to actually achieving these goals, Mr Mautz said. 

'You need to believe you’re allowed to dream big, that big things can happen to people like you,' the CNBC contributor wrote. 

Next, he recommended sharpening up your decision-making skills. In order to succeed in this category, mentally tough people often ask themselves: 'What’s the cost of indecision?' - or not making a decision at all.

Indecisiveness can be a sign of underlying problems, like low self-esteem, a fear of failure, or anxiety,  according to psychologists Drs Martin Self and Sally Winston, who run private practices in Connecticut and Maryland, respectively. 

In the time you take over-thinking a decision, you can lose out on opportunities, remain stuck in a bad situation, get left behind by peers and disappoint loved ones, Drs Self and Winston wrote.  

Having trouble making decisions can make you less successful in your work or personal life, and can make you less resilient against challenges that come up in either environment. 

Keeping these stakes in mind can help you remember that efficient decision making is important, and can help you avoid being bogged down in details that lead to indecision.  

Reminding yourself that indecision has stakes too can help you become a better decision maker and increase your mental toughness

Focusing on the things you can control helps you devote your energy toward the problems that require your energy

Next, Mr Mautz said mentally tough people have a realistic view of what they can and cannot control. 

Spending precious mental energy worrying about factors beyond your control distracts you from dedicating your full potential toward the task at hand.

In order to strengthen this personality trait, you can ask: ‘Am I controlling the controllable?’

For example, worrying about the weather for an upcoming event you planned isn't fruitful because you can't control what mother nature will decide to do. 

But you can make sure you've controlled for other factors, like ordering umbrellas or fans, in order to ensure you're prepared for whatever comes your way. 

Finally, the last phrase Mr Mautz recommended has you reframe arduous daily tasks as things you're grateful for. If you tell yourself, ‘I don’t have to do this; I get to do this’, you can help work towards more mental toughness. 

 'This one-word reframe unlocks gratitude, making you feel re-energized when the duties of your job are wearing you down,' Mr Mautz wrote for CNBC.

When you feel more positive about the tasks set in front of you, you're more likely to perform them with enthusiasm and execute them effectively.