DeMar DeRozan is tired of questions about his age. ‘You just make people eat their words,’ the 33-year-old Chicago Bulls forward says.

DeMar DeRozan is tired of being called old.

He’s tired of a lot of things. Questions about his toughness. About his fit with Zach LaVine and the Chicago Bulls. About whether he still has enough in the tank to make it another season.

As DeRozan enters his 14th NBA season, he is accustomed to shrugging off those doubts. But that doesn’t mean he’s immune to annoyance.

“It’s like, ‘God damn, what did I do to you all?’ ” DeRozan said with a laugh during Bulls media day Monday. “You look at so much stuff like it’s entertainment. You indulge in it, take whatever you want from it. You just make people eat their words and you get the last laugh. Because I know nobody understands and knows the amount of work that I put in. I know for a fact that most of the guys in our league don’t work like I do. Just me knowing that part of it, I already know what you’re putting up is BS.”

DeRozan’s 13th season in the league was his best — averaging a career-high 27.9 points, knocking down buzzer-beating shots on back-to-back nights and earning a starting spot in the All-Star Game — and newfound respect in Chicago.

And yet the doubts returned, constant and ever present, the moment the season ended. DeRozan turned 33 in August, seven years senior to the average age in the league (26.1). Even after a stellar season, DeRozan was surrounded by questions regarding his age. Was that the peak? Can he get any better at this point in his career?

That’s just another concept that perplexes him.

“Who comes up with that theory?” DeRozan said. “I always wondered that. It ain’t like I’m 48. … It’s not like I’m Kevin Willis out here.”

DeRozan can’t let himself think about slowing down. But he also thinks the concept is preposterous at his age, especially as he joins an elite group of veterans still dominating the league in their mid-30s. DeRozan spent time this summer with fellow veterans Chris Paul and LeBron James, who are finding new layers to their game at 37.

Although age always will be a factor, DeRozan believes advances in sports science are making it increasingly possible for players to extend their careers deep into their 30s.

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“There are so many ways to take care of yourself — physically, mentally, nutrition, the technology that you have for recovery,” DeRozan said. “There are so many ways that you can be effective for longer periods of time. … I love getting older just to show people you still can get better the older you get.”

Last season was an adjustment period for the Bulls. DeRozan fit right in, exceeding expectations while establishing himself as a locker-room leader.

Now, the Bulls know exactly what they’re getting from DeRozan.

“I just need him to be himself,” coach Billy Donovan said.

Even in DeRozan’s finest season, the Bulls often struggled when they asked him to do too much. Injuries forced stars Zach LaVine and Lonzo Ball to the sidelines for large swaths of the season. DeRozan rose to the occasion, delivering 40-point heroics whenever the Bulls needed them. But that wasn’t enough to lift the Bulls in the postseason.

After LaVine underwent surgery in the offseason, DeRozan is confident the duo will flourish.

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“It can be very exciting and scary for other people,” DeRozan said. “I can’t tell you how many times I talked to him this summer, just checking on him. I want be with a healthy Zach. A full year of that is something I dream about every single night.”

A believer in consistency, DeRozan’s offseason looked the same as his last 13 summers — a rigorous gym schedule balanced by time with family in Los Angeles.

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But DeRozan also welcomed young Bulls forward Patrick Williams into the routine, continuing to embrace a newfound role as a mentor.

“It’s an honor for those guys to even trust me, look toward me for any kind of advice,” DeRozan said. “Even this far in my career, I don’t think I’m bigger or better than the next guy. For guys to trust me with any kind of advice, to work out with me, to spend any time with me, it means a lot to me.”

Training with younger players and staying around his family help DeRozan keep in touch with the spark that ignited his love of basketball as a kid. Each summer, he focused on reconnecting with that joy while obsessing over the minute details of his game.

DeRozan isn’t quite at the point of turning off the lights in the gym to learn to shoot blind — a concept he joked about at media day. But he’s still finding ways to keep the game fresh for himself.

“I haven’t met nobody that has perfected anything in any type of craft,” DeRozan said. “As long as you’re adding something small — no matter how small it is — to something you already have, it’s beneficial. That’s how I look at it. There are still so many ways that this game can be figured out.”