Jane Brody's New York Times column of 2017-04-03, "Turning Negative Thinkers Into Positive Ones", suggests some routes toward building a healthier, happier, more productive mind:

• Do good things for other people — In addition to making others happier, this enhances your own positive feelings. ...
• Appreciate the world around you — It could be a bird, a tree, a beautiful sunrise or sunset or even an article of clothing someone is wearing. ...
• Develop and bolster relationships — Building strong social connections with friends or family members enhances feelings of self-worth and, long-term studies have shown, is associated with better health and a longer life. ...
• Establish goals that can be accomplished — Perhaps you want to improve your tennis or read more books. But be realistic; a goal that is impractical or too challenging can create unnecessary stress.
• Learn something new — It can be a sport, a language, an instrument or a game that instills a sense of achievement, self-confidence and resilience. But here, too, be realistic about how long this may take and be sure you have the time needed.
• Choose to accept yourself, flaws and all — Rather than imperfections and failures, focus on your positive attributes and achievements. The loveliest people I know have none of the external features of loveliness but shine with the internal beauty of caring, compassion and consideration of others.
• Practice resilience — Rather than let loss, stress, failure or trauma overwhelm you, use them as learning experiences and steppingstones to a better future. Remember the expression: When life hands you a lemon, make lemonade.
• Practice mindfulness — Ruminating on past problems or future difficulties drains mental resources and steals attention from current pleasures. Let go of things you can't control and focus on the here-and-now. ...

(cf. Optimist Creed (1999-04-06), Don't Panic (2010-11-17), Thirty Things (2013-10-01), Happiness Buffer (2013-12-22), Habits of Unhappy People (2014-03-11), Negative Thinking Patterns (2015-08-28), Cognitive Distortions (2015-09-28), Mental Toughness (2015-12-06), Power of Optimism (2016-02-23), Mantra - Be on Good Form (2016-05-10), Sheryl Sandberg on the Hard Days (2016-05-22), ...) - ^z - 2017-09-21