Transition psychology originated from work on bereavement, family crisis, and depression. Models of transition describe how individuals respond to changes in their lives or environment. Most transitions are associated with significant life events that require radical restructuring of one's view of themselves and the world, and this process typically takes 6-12 months or longer. Transitions involve grieving the old and readjusting to the new, are best approached intentionally, and work best when an individual understands the challenges and has supports to help cope.