Complex sentence: At the age of 12 she spent 6 months in hospital with pneumonia which severely reduced her lung capacity and thus prevented her from ever playing sports or singing professionally, which had been her ambitions, and eventually led to her choice of a career in the media.
Split into simpler sentences: At the age of 12 she spent 6 months in hospital with pneumonia, which severely reduced her lung capacity. This prevented her from ever playing sports or singing professionally, which had been her ambitions, and eventually led to her choice of a career in the media.