How difference "take a deep breath in" and "take a deep breath"?
Native speaker’s answer
Rebecca
There is not much of a difference between "take a deep breath in" and "take a deep breath". The preposition "in" here is just used to specify the direction of the breath which is "in". Most deep breaths are taken inwards, however, when someone exhales, it is often referred to as taking a deep breath "out". Therefore "in" just emphasizes the action of breathing inward. Ex: Take a deep breath in and hold it. Now take a deep breath out.