In a world where many of us are glued to our smartphones, Dulcie Cowling is something of an anomaly - she has ditched hers. The 36-year-old decided at the end of last year that getting rid of her handset would improve her mental health. So, over Christmas she told her family and friends that she was switching to an old Nokia phone that could only make and receive calls and text messages. She recalls that one of the pivotal moments that led to her decision was a day at the park with her two boys, aged six and three: "I...