Complex sentence: After watching Michael J. Fox's guitar performance as Marty McFly in "Back to the Future", Mayer became fascinated with the instrument, and when he turned 13, his father rented one for him.
Split into simpler sentences: After watching Michael J. Fox's guitar performance as Marty McFly in "Back to the Future", Mayer became fascinated with the instrument. When he turned 13, his father rented one for him.