“I grew up in this area, I have been on the streets, I have lived the wrong life,” he added.
“Pain has purpose. If you don’t have that pain, you are not going to get to your best self.”
After turning professional at 28, Valentine won seven of his 10 fights and was crowned the Midlands WBC champion in 2012.
But he felt choices he made at the time meant he never fulfilled his full potential as a boxer.
He said: “Just before I started this [bootcamp], I wasn’t in a good place.
“I said enough was enough and I was going to turn my life around.
“I went for a jog around the Forest Recreation Ground, I started doing some pull ups at the park bit at the bottom.”
Valentine said he started inviting people to come and train with him at the park and it “grew and grew”.
“After about two years I got a building in Forest Fields and that got busy,” he said.
“Kids were coming in with no confidence but a few months later they were confident.
“I could see what it was doing for them.”