Nike unleashed a potent new ad Monday featuring Colin Kaepernick on Monday. The ad is simply a portrait of Kaepernick with the message "Believe in something. Even if it means sacrificing everything. Just do it."

The message clearly alludes to Kaepernick sacrificing his career as an NFL quarterback (at least over the past few years, anyway) after peacefully protesting racial injustices and police brutality in America by kneeling during the national anthem prior to games -- a gesture that sparked plenty of criticism and also sparked major social discussion and a cultural movement across the sports landscape.

Believe in something, even if it means sacrificing everything. #JustDoIt

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Kaepernick, 30, hasn't played in the NFL since 2016. He opted out of his deal with the San Francisco 49ers following that season but hasn't signed another NFL deal since, something that he claims is a result of NFL owners colluding to keep him out of the league. He has an active grievance case against the league over this issue.

Nike has kept Kaepernick on the payroll throughout the entire saga, presumably waiting to feature him in a powerful and meaningful campaign like the one above. Now, he's the face of Nike's 30th anniversary "Just Do It" campaign.

And while Kaepernick has been somewhat elusive over the past few years -- he's picked his spots when it's come to speaking publicly and stepping into the spotlight -- his presence remains felt in the NFL (and across sports), even if he's not on a roster. He has received a large amount of support from athletes throughout his campaign for racial equality.

That remained true on Monday following the release of his new Nike campaign.

Not unexpectedly, the ad also also sparked more negative reactions from various folks online; all you need to do is go through Kaepernick's mentions to get a glimpse at some of those responses. But there seems to be entirely positive feedback from his peers, and the campaign will likely generate plenty of discussion in the coming days and weeks.