I have a video tape presentation done by Peppo Biscarini three years ago and he gave some excellent information about breathing techniques that I have been using that seem to work for me as part of my daily training.
It entails this pattern: 5-5-5-5
5 seconds to fully inhale, 5 second breath hold, 5 seconds to fully exhale, 5 second breath hold from the exhale - repeat. I do this for 5 minutes and then go to a 10-10-10-10 routine for another 5 minutes.
Feels like I have had a mini-vacation.
Have tried to go 15-15-15-15 - so far I can't make it through one cycle without gasping on the second inhale.