The Christian broadcaster also described Jesus as her "anchor" in a "very competitive industry" which can leave people feeling "really, really insecure".
Speaking about her arrival at Blue Peter in 1990, Diane-Louise said: "There were so many other people who could have easily filled my shoes.
"It so says to me that if God wants you to be there (he really does order your steps) you will be there, and he doesn't want you to be there, you won't."
The 58 year old will join other former Blue Peter presenters including Peter Purves and Konnie Huq in celebrating the milestone during a grand reunion on Tuesday.
She went on to say: "We're like five-year-olds going to their first birthday party.
"We're so excited that we all going out to see each other...and have this confidence that Blue Peter is probably going to be around for another 60 years."
Diane-Louise, who currently presents Songs of Praise on BBC One worked on Blue Peter for six years, becoming one of the show's longest-serving presenters.
Describing how she has coped with the pressure of working in television, she added: "Whether I'm in a great job, or whether I'm working or not working... it doesn't matter because my anchor in Jesus.
"Wherever he wants me to be, that's where I'll be. Whatever he wants me to be doing, that's what I'm going to be doing."
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