People who are mentally healthy:

• have a sense of contentment

• can deal with stress & bounce back from difficulty

• have a sense of purpose & meaning

• can build & maintain healthy relationships

• are flexible & can adapt to change

• balance work and play, rest and activity

• have self-confidence & self-esteem

Positive psychology is powerful because it can be applied to any aspect of our lives. 

Happiness isn't determined by external factors—it's a product of our mindset. Improving our outlook manifests more positive results in reality, which reinforces our positive mindset and creates a feedback loop that leads to further positive outcomes and greater happiness. 

Book Recommendation
The Happiness Advantage — Shawn Achor.  Based on a decade of research, this book challenges the idea that if we work hard and become successful, we'll be happy. It shows instead that happiness is a precursor to success, not a result of it, and proposes a proven seven-step framework with simple everyday actions to cultivate a positive mindset and create positive, lasting change