Complex sentence: Lionel Khoo, who was always scared of entering the pool, started swimming at the age of three after he was pushed into pool by a childhood friend, and his parents signed him up for swimming lessons.
Split into simpler sentences: Lionel Khoo, who was always scared of entering the pool, started swimming at the age of three after he was pushed into pool by a childhood friend. I was pushed into it by a childhood friend, after his parents signed him up for swimming lessons.