Want to know the greatest indicator of success? Psychologist Angela Lee Duckworth’s research looked at West Point Military Academy cadets to try to predict the top graduates; they went to the National Spelling Bee to identify the stars; they studied rookie teachers in tough neighborhoods to see who would survive and thrive; and in the corporate world, they looked at the qualities of the most successful salespeople. In all those different settings, one characteristic stood out as the greatest predictor of success. It wasn’t good looks, physical health, family connections, or intelligence; it was mental toughness.

Mentally tough people are gritty and resilient. They’re able to keep pressing on when everyone else has given up. We can all learn to become mentally tough. Here are six ways:

1. Reframing negatives.

Cognitive reappraisal techniques are foundational in psychotherapy and mental health. It’s the ability to approach and see negative situations from a different angle. In simple terms, it’s seeing the glass half-full, and looking for the silver lining.

Mentally tough people aren’t immune to failure and losing; they still get hurt, frustrated, and angry. But they move beyond those emotions through reframing techniques. Every negative situation has a teaching point and lesson to be learned — if you choose to look for it.

Ask yourself: “What has this experience taught me?” Or, “What can I do differently or better next time?”

2. The willpower trinity.

Mental toughness goes hand-in-hand with willpower. Our struggle with willpower comes down to a one-dimensional approach, according to Psychologist Kelly McGonigal. We rely solely on “I won’t” power — telling yourself you cannot or will not engage in a restricted activity. For example, those on a diet will say they aren’t allowed, or will not eat, dessert. But we fail to capitalize on two important other powers: “I will,” and “I want.”

“I will” power is a behavior-replacement strategy — replacing the notion that you cannot have dessert with a healthy alternative – I will have fruit or yogurt. “I want” power is to remind you of your source of motivation — I want to lose weight in order to play sport with my children.

The three “I will” powers come together to cultivate mental toughness, it will push you through the times you want to quit, or when you feel weak in your willpower.

3. You are what you eat.

Mental strength comes from healthy brains. Adopting a lifestyle of unprocessed foods without additives and preservatives will lead to a healthy body and mind. Drinking enough water feeds your brain the oxygen it needs. And getting enough sleep each night ensures you’re able to perform mentally at your peak.

Make your health a priority; take inventory of the food that you have in your home and what you snack on. You cannot be mentally tough if you are physically neglected.

4. Emotional cleansing.

Mentally tough people are able to process their emotions in a healthy and effective manner. Those who ignore, bottle up, or refuse to deal with negative emotions are setting up a time-bomb for mental breakdowns.

Emotions are powerful, but not always reasonable. Having the ability to detach from them and question their validity is a trait of a mentally tough person. Meditation and journaling are two powerful techniques for emotional processing and cleansing. Act as an observer, label the emotions that you are experiencing, listen and take action on what is valid; process and let go of what is not.

5. Process orientation.

Mental toughness is having mental endurance. It’s the old cliché of running marathons instead of sprints. Being persistent comes down to seeing your skills and intelligence as fluid and iterative, rather than fixed and immutable. The more time a mentally tough person spends on a problem, the closer they believe they are to cracking the code. Never for a minute do they believe they’re not smart enough or incapable.

It’s been referred to as the “growth mindset.” Embracing the process as a valuable learning experience will allow you to stick to a task much longer, regardless of how challenging it may be.

6. Mental workouts.

Just as going to the gym and lifting heavy weights improves your physique, intellectual challenges will boost your mental strength. Although excessive television has been shown to have detrimental effects on mental health, the bigger issue is not how much is being watched, but what is being watched.

Expose yourself to material that stretches and stimulates your mind. Read books that are more challenging than you’re used to. Watch documentaries that will bring about intellectual growth. Start working out your brain as much as your body.