The 35-year-old has not played football since a spell with Spanish side Real Oviedo in 2001.
Collymore told The Mirror: “I’ve had physical tests and I’m confident I will come back faster, stronger and fitter than I ever was.
“A month from today I guarantee I will be able to stand side by side with any striker in the country and my physique will be up there with any of them.
“This time I’m not going to self-destruct.
“You are not going to see headlines about me being kicked out of a bar somewhere in the early hours rolling drunk.
“I know I can still be among the best.”