The quality of life should be as important as the quantity of life. People are living 30 years longer than the start of the 20th century yet they are not living healthier. People can improve their wellbeing by using positive psychology. To be healthy we need to flourish rather than languish. Flourishing allows less days of missing work as you experience fewer health problems and therefore create a better sense of purpose.
One of the biggest mindset changes you can make is how you view happiness, as most tend to equate it with feeling good. We set up an impossible task because our hedonistic version of happiness is impossible to maintain.