Improved by a positive attitude. The word must have 12 letters.

The word you're looking for that means "improved by a positive attitude" and has 12 letters is "embetterment."

The word "embetterment" isn't commonly used in everyday English but it suggests the idea of improving a situation, condition, or oneself, often through a positive approach or attitude. The word can be broken down into "em-" meaning "cause to be; make" and "-betterment" from "better," which means to enhance or improve. It's often our attitude towards life's challenges that determines our experience and, by adopting a positive outlook, we can sometimes bring about significant improvements in various aspects of our lives, including personal growth, professional success, and relationships. This concept ties in with positive psychology, which is a field of psychology focusing on what improves the quality of people's lives and what makes them flourish rather than on mental illness or psychological problems.