The methodology seems strange. Questionnaires were compared based on whether yoga students had just done yoga, vs not in 24 hours (but presumably do yoga regula

The methodology seems strange. Questionnaires were compared based on whether yoga students had just done yoga, vs not in 24 hours (but presumably do yoga regularly). So essentially, there's a statistically significant correlation with time from last session, but it doesn't say anything about correlation with frequency of sessions. And as usual, correlation is not causation. Was there a control group with another physical activity? Reading? Solving Sudoku puzzles? One could also postulate a perfectly reasonable-sounding theory that people's egos get bigger with any activity where there's a surge in endorphins, regardless of whether that activity is yoga or not.