Rach loves a good surprise -- and we have to say, this was one of her best!

When “The Biggest Loser’s” Bob Harper told us the story of his career, we had to reunite him with the woman to whom he credits his start in the fitness world -- a woman named Elaine.

Bob’s first foray into fitness was at a studio in Nashville, Tennessee -- owned by Elaine. He calls her “instrumental” to his growth as a trainer, but not even Elaine knew the impact she had on him -- until she got a call from our producers.

Elaine hid in our studio audience until Rach revealed her to Bob -- and the two had emotional reunion you have to see for yourself!

Watch it all go down in the video above. But maybe grab some tissues first!