'Biggest Loser' Trainer Bob Harper Celebrates 60th Birthday: 'I’m So Lucky' originally appeared on Parade. Fitness icon Bob Harper knows how lucky he is to be alive on his 60th birthday.

For years, Bob Harper and Jillian Michaels appeared to have great chemistry onscreen while filming "The Biggest Loser" together. But a new docuseries about the NBC weight-loss competition has fans wondering if the dynamic duo actually got along in real life.