NEW YORK -- If you're new to the Coco Gauff Show, here's some important context: She wasn't always like this. 

Bursting onto the scene as a 15-year-old by defeating Venus Williams at Wimbledon, Gauff's poise far outpaced her speed and serve. Which is saying something about her poise.

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She had all the affectations of a typical teenager -- her musical tastes, her TikTok obsessions, her deep meme database -- but on the court and in the interview room, Gauff had the air of a seasoned veteran. 

It all sent a very clear message from the start. Tennis is a serious business and this precocious prodigy treated it as such. Aside from the occasional "Come on!", she was a focused and stoic figure on the court. Losses felt heavy. Wins felt like a relief. 

All that's changed. For the better.

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Since her crushing first-round loss to Sofia Kenin at Wimbledon, Gauff has now won 16 of her last 17 matches. Over that span, she has one-upped a trio of milestones. Washington D.C. was her first WTA 500 title. Cincinnati was her first WTA 1000 title. Now into the US Open semifinals, it's her deepest run at her home Slam. 

And she's doing it all with a youthful exuberance that she had kept locked away for the first four years of her career.

"Honestly, I wish I embraced the fun parts a little bit sooner," Gauff said after her 6-0, 6-2 win over Jelena Ostapenko in the quarterfinals.

"I thought to play and win you have to be ultra serious and ultra-focused, which that is true, but also you still have to enjoy it. I think that's what's been the change is that I'm having more fun."

Gauff credits a conversation during her first sit-down with coaching consultant Brad Gilbert. The first piece of advice he gave her? Smile more. 

"I really took that, and when he said that I was a little bit surprised," Gauff said. "I started to think and I was like, yeah, I do [need to do that]. That's something I'm trying to work on and continuing to do, and obviously I think it's helping my results."

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It all started in Washington D.C., where she gleefully - and uncharacteristically - celebrated after particularly electric points. In Montreal, stuck on an outer court to play a rain-delayed match against Wimbledon champion Marketa Vondrousova in front of a handful of fans, she laughed and went about her business. In Cincinnati, she cracked jokes with her box during matches.

"[In] individual sports you don't have the one teammate that always is making jokes or the one teammate that maybe messes up at the wrong moment where you can laugh at," she said. "So it's really just you. 

"I'm just being all those types of teammates for myself and I'm enjoying it."

So yes, tennis is serious business. Gauff is the youngest American, man or woman, to make the US Open semifinals since Serena Williams in 2001. She faces an opponent she routined two weeks ago for a spot in her second Grand Slam final. She's a 19-year-old from Florida who is packing the biggest tennis court in the world with A-list celebrities like Justin Bieber and the Obamas. 

The stakes are high and Gauff does not take it lightly. But whereas she found herself emotionally drained by the end of her deep runs in the past, this year Gauff says she feels remarkably fresh for her push into the final four.

"When I was a kid, I just thought about winning tournaments," Gauff said. "The dreams never came with the people in the stands and autographs. That was never in the dreams. It was just the trophy.

"I guess I never prepared myself for it. In hindsight, I think the amount of people that I've met doing this and the amount of people that come up to me just saying nice things and saying I helped them makes it all worth it." 

Of course, Gauff's ability to enjoy herself more on court isn't just about slapping a smile on her face. It all comes from the grounded perspective she learned to understand and embrace.

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Before the US Open, Gauff said she loved going to Times Square to just people-watch. Part of it was for pure entertainment, but her excursions also reminded her how many people are living their lives without one concern about whether Coco Gauff wins or loses a tennis match. 

"At first, I used to think negative things, like, why is there so much pressure, why is this so hard, blah, blah, blah," Gauff said. "I realized, in a way, it's pressure but it's not. There are people struggling to feed their families, people who don't know where their next meal is going to come from, people who have to pay their bills. That's real pressure, that's real hardship, that's real life. 

"So instead of saying 'Why this, why that', I should just be, like, 'Why not me?"

"I'm living a lucky life and I'm so blessed. I don't want to take it for granted."