Broncos linebacker Von Miller has changed his ways.

Perhaps you could say he’s grown up. But he’ll just tell you he’s learned more about himself, more about the game, more about what works and what doesn’t after four seasons in the NFL.

After spending last offseason rehabbing from a knee injury, Miller has taken advantage of his good health this year, refusing to take a day off and putting a greater emphasis on his nutrition and training.

In speaking to local media at the Broncos’ Dove Valley headquarters Wednesday, the three-time Pro Bowler said he’s in better shape than he’s ever been, a result of holding himself more accountable and pushing himself further than ever.

“I was in pretty good shape last year, but I want to go to another level. It’s always about how far you can push yourself and how much you can better yourself,” Miller said. “I definitely feel like I’m in better shape than I was coming in to OTAs (organized team activities), and I feel like I’ll be in better shape going into training camp.”

It started with his nutrition. Gone are the burgers, steaks, juice and pork. In are chicken, fish, broccoli and a gallon of water a day.

Miller, who said he weighed 252 pounds at his heaviest last year, said he is down to 242.

“Sometimes you just have to step away from the burgers and stuff,” he said. “It might not be hurting you, but it’s definitely not helping you.”

The change for Miller is just one of many to the Broncos’ defense this offseason with the arrival of defensive coordinator Wade Phillips and a 3-4 scheme. Miller said the Broncos have the talent to be the league’s top defense.

“Every year I play out here, every time we come into a new season, I feel like we’ll be the No. 1 defense,” he said. “I’ve never been on any team, back in college or little league football, where I’ve gone into a season thinking, ‘Oh, we’re going to be all right this year.’ I’ve always had that positive mindset, ‘We’re going to be the best defense,’ ‘We’re going to be the best team out there,’ or ‘I’m going to be the best player in the NFL this year.’ I always go into the season with that mindset, and this year is no different.”

His optimism for 2015 might be amplified by his own improvement off the field. Miller said he hopes the changes he’s made to himself are evident on the field. He hopes he comes out, and finishes, even better than he did last year, when he made 14 sacks and 59 combined tackles.

“When the fourth quarter rolls around, I don’t want to be thinking about the ice cream I had the night before,” he said. “I want to be thinking that I’m proud and that I’m in the best situation that I can possibly be in.”

Nicki Jhabvala: njhabvala@denverpost.com or twitter.com/nickijhabvala