"Tuck your tailbone under" is a cue often heard in poses like utkatasana (chair pose) and anjaneyasana (low lunge) to encourage a neutral pelvis. But most students actually end up tipping their pelvis backward when they tuck, which can place unnecessary stress on the lower spine and surrounding muscles. Jonina explains "why not to tuck" in your yoga practice and daily life, and what you should be doing with your sacral area instead.