Shelvey signed a long-term deal earlier this year and after emerging as Newcastle's top scorer this season he has been hailed by team-mates.
He told talkSPORT: "As soon as you do one bad thing you just get this reputation that you are a bit of an idiot.
"People who have played with me know that deep down I am a good person and a good guy.
"I'd do anything for my team-mates.
"I feel like I am in the right mindset.
"I am 28 now and that is when players come into their peak.
"I have felt stronger and fitter in my body.
"It has put me in a better place in terms of mind-set.
"Long may it continue, I can progress and carry on kicking on."