Philadelphia, Pennsylvania - Jason Kelce dished on the "staggering" changes he's seen in his brother Travis since the Kansas City Chiefs star began dating Taylor Swift.

The 37-year-old retired NFL star appeared on the Fitz & Whit podcast on Tuesday, where he opened up about his perspective on the high-profile love story.

When co-host Ryan Fitzpatrick joked about Travis having a bit of Peter Pan syndrome, Jason shared that his brother's growth has been "staggering" over the last two years.

"It's changing, and I think that sometimes, you get people in your life that maybe get that out of you, and that's a good thing," the former Philadelphia Eagle said, alluding to Travis' romance with Taylor.

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Though Travis may be properly growing up these days, Jason said that the 35-year-old still has plenty of "youthful enthusiasm" and said he's a "free spirit in the best possible way."

Jason's comments come as Travis reportedly eyes another major life change: retiring from the NFL.

After the Chiefs' brutal loss at Super Bowl LIX earlier this month, the tight end is weighing whether or not to retire from the NFL, and he's reportedly been handed a deadline of March 14 to make the decision.

According to Us Weekly, Taylor "will support him" no matter what he chooses to do.

Insiders dished last month that two "ideally" want to settle down "in one home as they start a family" when they are ready to take that step – likely after a potential retirement.