The 46-year-old popped his top for a workout down in Florida on Thursday ... and you can see the dude's still got chiseled abs, bulging biceps and a pair of defined pecs -- even though he hasn't played a down in the NFL in nearly two years.

It's apparent the muscles ain't just for show, too ... check out the footage of Brady running some wind sprints -- the ex-quarterback can still move!

Brady was obviously impressed with what he's still got left in his tank, as he captioned the footage, "24 years later..."

"@nobull. no excuses," he continued. "Show up for yourself so you can show up all damn day!"

While the clip was clearly meant to be an advert for his NoBull company ... it's certainly going to add more fuel to the unretirement fire he started last week.

If you missed it, on the "DeepCut" podcast, Brady admitted that if a team needed him in an emergency situation next season, he would at least consider it. But, he laughed when he made the comment -- leading many to wonder exactly how serious he was.