Both lifestyle and health are affected. When children leave the nest, the result can be a challenge or an opportunity. Divorce becomes more common. Some people re-enter the work force. Others retire early, or find themselves out of a job for the first time in their lives.
Some people find their middle years the happiest and most productive time of their lives.
Others suffer a mid-life crisis, or even go through a major depression. The needs of aging parents also become an issue. Bodily changes can serve as a reminder that we need to take better care of ourselves. Health issues can become serious concerns. Heart disease, cancer, and stroke become diseases that don't just happen to other people.