The Magpies' prospective owners are reportedly keen to replace Bruce with a higher-profile manager.
But Shelvey says Bruce has done a great job since joining last summer.
"It's been great to be fair," Shelvey told talkSPORT.
"Every time you get a new manager you feel refreshed and recharged and ready to go again.
"When you get a new manager it's like the first day back at school. Everybody is trying to run around and look busy.
"You want his attention and to try to make an impression. The training and standard has gone up.
"He's brought an enjoyment into the training but he's been great for me.
"He put his arm around me and made me work harder."