If you can find a way to use your signature strengths at work often, and you also see your work as contributing to the greater good, you have a calling.  Your job is transformed from a burdensome means into a gratification.  The best understood aspect of happiness during the workday is having flow, feeling completely at home within yourself when you work.
Martin E. P. Seligman, Ph.D., bestselling author of Learned Optimism and Authentic Happiness

Gandhi, Eleanor Roosevelt, Mother Teresa of Calcutta, Walt Whitman: the names of famous peope who began anew in the midst of adult life transitions are plentiful.  Some discovered what they really wanted and then made their changes; others found life taking the lead and only subsequently found in transitions that they didn’t want to make the opportunities to do what they seem to have been desitined to do.
- William Bridges, Transitions: Making Sense of Life’s Changes