The phrase comes from American bodybuilder Ronnie Coleman, an eight-time Mr. Olympia winner known for training with extremely heavy weights while shouting encouragement at himself. Clips from his workout videos circulated online in the 2000s and 2010s, and light weight baby became one of his most quoted catchphrases alongside yeah buddy. Gym communities adopted the audio for motivation, then meme editors began using it ironically for everyday tasks. Its mix of genuine intensity and over-the-top delivery keeps it popular on social platforms, in fitness edits, and on soundboards today.