The singer rose to fame as a member of the chart-topping group but, speaking to Britain's You magazine, she admits she wasn't initially convinced returning to the band was a good idea, as she was nervous about revisiting the past.
"Going back isn't just about going back to be with the girls - which is great; it's also going back to those emotions of who you were in the band," the 48-year-old British singer says.
"I did talk to my therapist a lot about those feelings. I was concerned about having to become Sporty Spice again," explains the "I Turn To You" hitmaker. "Then it just hit me that I am her, but I'm older and happier and I have so much more confidence."
"Once I realised that, it was a game-changer. And the reunion tour was magical," smiles Mel. "The fans were there to have the best time and they were looking fantastic."
"We all had our kids there. We sang in the sun and the rain. Of all the tours it was, for me, the most special."
Ahead of the group's 25th anniversary in 2021, Mel teases she and bandmates Emma Bunton, Geri Halliwell and Mel B (Melanie Brown) have been chatting with Victoria Adams - who sat out the last jaunt - about plans to mark the milestone.
"We have our WhatsApp group and we are all talking but I can't say more than that," she teases.