I stumbled upon this: it can make you realize what breathing can do for you. It has a huge effect on one's mental state: it almost instantly calms you down.
Try breathing in sync with this (just for fun):
i.imgur.com/Huou7Gh.gifThese are a few breathing techniques that work really well:
... When you feel anxious
Slowly breath in through your nose
Hold your breath for a few seconds
Breath out even more slowly through your mouthh. Try to make your exhalation take longer than your inhalation. You may structure your breathing if you'd like, by counting to 4 as you breathe in, to 2 as you hold the breath, and to 7 as you breathe out.
... When you feel sluggish (be careful if you hyperventilate easily)
Breath in and out as fast as you can.
Make your inbreath and outbreathof equal length.
At first, do this for 15-20 seconds. You can progress up to 1min.
Make it shorter if you experience light headedness.