I learned deep breathing years ago when I started meditating on a regular basis. I also used it when I worked in hospital to calm patients down. It's a great trick for when someone is hyperventilating.

It was easier for me to practice lying down at first and actually watch and feel my belly go *up*/out with each deep breath, knowing I was filling my lungs up fully; then I would relax and blow out all of the air, until it felt as though there was none left, yet a bit more always made it out.

This has stood me in good stead. When I had to go on O2 for my heart, the docs couldn't believe how deep my breaths were and how long I could "blow out" on their test machines. It is also the only way I can be sure I have enough air to sing.

Just takes practice.

kat