Grealish has endured a difficult few years at Villa Park, most notably when the youngster encountered a life-threatening injury when he split his kidney in two places during a pre-season friendly, but has since returned to the pitch to prove vital to Villa's push to the playoffs.
"I feel like I have grown up," said Grealish, according to Sky Sports News. "You learn things, especially around the likes of JT, Mile [Jedinak] and Snoddy (Robert Snodgrass), they're in your ear all the time in a good way, telling you what to do on and off the pitch.
"When [Terry] first came it was a big shock, I had to pinch myself a bit, and was a bit star-struck. But straight away you see the little bits of quality he does on the training pitch.
"He's been such a big help to me, and was one of the first people to call me in hospital. He's first in, last out, and does everything. Whether massages, in the gym or pool after training, he does everything right."
Villa face Fulham in the Championship playoff final on Saturday evening at Wembley Stadium for a place in the Premier League next term.