Walt -- the #9 ranked heavyweight -- is now set to fight Alistair Overeem on Saturday night ... and tells us getting back work is part of the grieving process.
"It's proof that you can go through the worst thing you can possibly think of in your life, and bounce back," Harris said.
"I’m so grateful to the UFC, and to the fans, and everybody who’s supported me through all of this. And, that’s kinda been my motivation, that's why I want to go in there and put a show on for them Saturday night and say thank you."
Harris said Aniah was his biggest fan who loved to watch him fight -- and he knows she'll be there in spirit on Saturday.
"I’m at peace, man. I love her so much, and I’m going to make her proud Saturday night."