Nat Ambrose from Virginia was not allowed to ride a roller coaster at Kings Dominion Theme Park, because of his weight. 

Ambrose weighed 300 pounds which prevented the coaster's safety harness to effectively restrain him. 

Ambrose was embarrassed by his inability to ride, and decided to lose 105 pounds. 

The feat took him nine months, he then returned to the park and rode the coaster.