I would generally always recommend to breathe deeply. Nearly everybody is breathing very superficially in our fast and hectic world although our breath is something so important, just necessary for living. Well, it is obvious why we tend to forget it: it happens automatically, we don’t have to do anything consciously about it. Our muscles do this part fully on their own. And we don’t give importance to it. We do not really realize it at all.
The whole science of Pranayama is about that: just being aware and conscious about your breathing. You are living anyway, surviving anyway, it will go on, you cannot stop it, but see how much benefit you can get from it if you actually do it consciously!
Do you sometimes just need to take a deep breath which comes out of nothing? This happens because your body needs oxygen and with your superficial breathing it didn’t get enough, so it takes it by forcing you to inhale deeply. If you get more aware of your breathing and increase the regular depth, your body will be very happy. Your lungs will get enough oxygen and also your brain will benefit from this. Several times a day you can actively remember this and just breathe.
In this moment it becomes Pranayama, it becomes meditation. Whenever you are aware, you are in meditation. Breathe, it is the essence of life.