An Idaho man broke a Guinness World Record when he caught 67 tennis balls in 30 seconds while standing on a balance board.David Rush, who has broken more than 100 records to promote STEM education, made his attempt in front of a live audience during a Growth Mindset conference at the Boise Center. Rush said he had to keep his knees straight and alternate hands with each catch to comply with Guinness' rules for the record, which previously stood at 30 catches.Rush stood on the balance board and managed 67 catches before the timer ran out.