In NASCAR, drivers speak freely about racing, but personal struggles often stay hidden until the time feels right. Dale Earnhardt Jr. kept quiet about his concussions for years. Kevin Harvick didn’t let feeling sick slow him down. And now, Denny Hamlin has shared a story he kept to himself, one of the hardest days he’s ever had in a race car.

Denny Hamlin, the Joe Gibbs Racing veteran, wrapped up the 2024 Cup Series with three wins at Bristol, Richmond, and Dover, plus a solid eighth-place points finish despite challenges like a hefty penalty after Bristol and a stuck throttle incident at Martinsville.

His season showed resilience, but it also highlighted how drivers sometimes push through without spilling the details. This isn’t new in NASCAR history. Like Dale Earnhardt Jr., who concealed over 20 concussions during his career, only revealing the extent in his 2018 book “Racing to the Finish” and interviews, years after symptoms forced him to step away.

It’s a reminder that health battles often stay under wraps. And lately, we’ve seen value in those stories, like Kevin Harvick grinding through a “deathly sick” state to finish fourth in a 2024 CARS Tour race at Las Vegas, proving drivers don’t always bow out when feeling rough. Denny Hamlin’s recent confession fits right into this pattern, pulling back the curtain on a hidden ordeal.

Denny Hamlin’s hidden Iowa’s agony exposed

Denny Hamlin finally opened up about his toughest day behind the wheel during a chat with Jeff Gluck in the “12 Questions” series, pinpointing last year’s Iowa Speedway race as his worst pain-wise. “No one really knew about it, but I came down with a fever, which weakened my body, and then I threw out my back,” Hamlin said. “I remember during pit stops telling the jackman, ‘You can’t just drop the jack; you need to squeeze it down.’ I was in bad, bad shape.”

That June 16, 2024, Cup Series debut at Iowa saw him start 12th but quickly fall two laps down early, finishing a dismal 24th, far from his usual contending form. The revelation underscores how health can derail even the best. Hamlin admitted he skipped mentioning it on his podcast, just “blew that over,” despite starting the race feeling “so horrible.”

In NASCAR, where drivers endure G-forces, heat over 130 degrees, and 400-lap marathons, physical fitness is non-negotiable. Jimmie Johnson credited his seven championships partly to rigorous training that built endurance and focus. Teams even have dedicated physicians like Bill Heisel to keep everyone race-ready, as injuries or illnesses can spike crash risks or drop performance sharply.

This isn’t Hamlin’s first brush with pain; back in 2020, he raced through a torn labrum in his shoulder, clinching wins while managing the hurt. But Iowa stood out because the fever-back combo hit hard, forcing adjustments like gentler jack drops to avoid agony.

It shows why mental health resources, now prioritized by NASCAR with comprehensive programs, matter too, staying sharp amid discomfort keeps drivers safe and competitive. While Hamlin reflects on tough days, he’s quick to spotlight emerging stars shaking up the series. One name that’s got him buzzing? Conor Zilisch.

Hamlin praises Zilisch’s dominance

Denny Hamlin didn’t hold back on his “Actions Detrimental” podcast, calling Conor Zilisch‘s recent Xfinity Series runs “wildly impressive” after the 19-year-old’s Watkins Glen win despite a post-race collarbone fracture. “Watching his racecraft while the chaos is going on, he’s still hitting his marks and passing cleanly,” Hamlin noted, highlighting how Zilisch manipulated the field with aero tactics on the Xfinity platform. That victory marked Zilisch’s sixth in the 2025 season, putting him atop the standings with five poles and 22 starts.

Hamlin drew parallels to Shane van Gisbergen‘s Cup impact, saying, “The gap that SvG has on us in the Cup Series, Conor has almost double that advantage over all the Xfinity.” Zilisch’s lap times at Watkins Glen were untouchable, six to seven tenths quicker than rivals, allowing him to charge from fifth to first swiftly.

Building on his 2024 feats, like winning the Rolex 24 at Daytona and the 12 Hours of Sebring in LMP2, plus five ARCA triumphs, Zilisch has proven versatile across disciplines.

Looking ahead, Hamlin marveled at Zilisch’s youth. “Can you imagine Conor with 20 more years of experience? Because that’s how old he’ll be when he gets to SvG’s age. Like, what the f–k.”

As part of Trackhouse Racing’s development and set for JR Motorsports in Xfinity, Zilisch’s poles at COTA and Bristol in Trucks last year signal big potential. Hamlin’s praise spotlights how phenoms like this keep NASCAR evolving, blending raw speed with smart racing.