Over time we all develop core beliefs based on our experiences about ourselves and the world. Whether you’re aware of them or not, they influence your thoughts, behaviors and emotions.Identify and evaluate your core beliefs to ensure yours aren’t inaccurate and unproductive, or even harmful. Look for beliefs that are black and white, and then find exceptions to the rule.

Evaluate Your Core Beliefs

Ruminating about things you can’t control drains mental energy quickly, leaving you less energy for what you can control. The more you practice expending your mental energy wisely, the more it will become a habit.Save your mental energy for productive tasks, such as solving problems or setting goals.

Use Your Mental Energy Wisely

Mental strength requires you to accept and be acutely aware of your emotions so you can respond better and consciously.Mental strength also involves an understanding of when it makes sense to behave contrary to your emotions and enduring the discomfort that comes with it. Practice behaving like the person you’d like to become.

Practice Tolerating Discomfort

Exaggerated, negative thoughts, can spiral out of control and influence your behavior if you don’t catch them.Replace overly negative thoughts with productive and realistic ones. Changing your thoughts requires constant monitoring, but the process can be instrumental in helping you become your best self.

Replace Negative Thoughts With Productive Ones

Developing mental strength is a work in progress. Reflecting upon your progress can reinforce your ability to reach your definition of success while living according to your values.At the end of each day, ask yourself what you’ve learned about your thoughts, emotions and behavior. Consider what you hope to improve upon tomorrow.

Reflect On Your Progress Daily

The following guest post is by Amy Morin, a licensed clinical social worker in Lincoln, Maine. In addition to working as a psychotherapist, she is also an adjunct college psychology instructor and she serves as About.com's Parenting Teens expert. Psychology often discusses mental health -- but what's not often discussed is a clear definition of mental strength.