What's with all these ex-boy band members getting into ridiculously ripped shape?!

Former boy band member Ashley Parker Angel -- who aside from being in O-Town, fans will recognize from his MTV reality show There and Back -- is no stranger to taking to social media to show off the incredible physique. On Thursday, he took it one step further by going completely nude on Instagram.

Ashley credited his jaw-dropping body to a 100-day fitness challenge. "During the last 100 days your positive comments motivated me to push through and stay committed," the 34-year-old star wrote. "I encourage all of you to experience for yourself how rewarding it is to set your own goals and get inspired by the results. You don't have to be a fitness model or featured in the ESPN Body Issue to be proud of your physique."

PHOTO: Ashley Parker Angel Grabs His Bulge for Testicular Cancer Awareness

"We all have what it takes to be the best version of ourselves we can be," he added. " ... Shortly, you will look back at where you started and be astounded at how far you've come... and you might just be inspired enough to post a naked picture of yourself on Instagram."

Clearly, he has the results to back it up.

Seriously, does this guy live at the gym?!

So what's Ashley been up to now, aside from an intense fitness regimen? Last November, he joined the touring version of the musical Wicked, playing the part of the male lead character Fiyero Tigelaar.

WATCH: Ashley Parker Angel Auditions for One Direction!

Check out the video below to see when O-Town briefly reunited last November -- sadly, without Ashley -- for an appearance on VH1's Big Morning Buzz Live Hosted by Nick Lachey.