The YouTuber star looked notably different by the end of the challenge, which saw him stand up for five days straight ...

The latest TikTok craze involves lying on your stomach to combat poor posture and neck pain. Here's what to know about "adult tummy time" and whether it actually works.

The rules of the experiment were clear: the YouTuber could lie down for exactly eight hours at night, but he had to be upright the rest of the time.