Want it to really take you to cloud nine? 
Close your eyes.
Take a deep breath
Feel the the air flowing through your lungs
Feel the calmness flooding through your head. 
Do this 10 times
Allow yourself to enjoy each breath to the max
Then hold your breath after one big inhale
Listen to your heart. 
Feel each thump
Let that sound be your only company. 
Listen to it fade away as your heart rate slows to account for the lack of oxygen.
Feel yourself run out of oxygen
Don’t panic
Just stay in one spot. 
When you feel ready, and only when you feel ready, take a breath in
Do not let your body dictate to you when to take that breath in just because it’s panicking.
You choose when. 
Take fifteeen deep breaths. 
It’ll feel much more different now.
Repeat the process until as much as you want. 
But three times is fine
You’ll sleep like an angel
I enjoy these kinds of breathing exercises but they only make me more energized... :)
Goo Gle