Grealish was caught flouting lockdown laws during the coronavirus crisis by attending a party and was forced to make a public apology.
"As an older guy now, looking now at some of these young kids, older players now should be able to pick the phone up and say 'have a think about that - have a word about that'," Collymore told SiriusXM.
"I did that with Jack Grealish. I sent him a long email when he went to a party. I told him he needs to make amends. I said to him 'you've got good people around you, you've let them down but now it's time to get back on track'.
"Pretty much as a prescription, he did everything that I requested he did. He made a big donation to a local hospital and he was forgiven.
"A big conversation - make sure the football family, doctors, clubs, keep their phone lines open because players are humans like we all are."