Just a word of caution for those of you who haven't done breathing practices before. You can hurt yourself badly if you are not careful. You can injure your lungs. This will be indicated by persistent coughing, and a painful sensation in the lungs. It may take weeks to heal. So do not inhale to your maximum extent -- leave a little room at the top. Similarly, do not exhale to the maximum, leave a little in reserve. By the way, very few people will be able to hold their breath for a full minute right off the bat, let alone for 90 seconds. It takes practice to work up to a full minute. There is no particular useful effect in holding the breath for this long. I've studied yoga breathing exercises -- the real thing -- and I don't think much of this guy's exercises. For one thing, they are way too strenuous. But if you want to give them a try, knock yourself out. Just remember what I'm telling you about not exhaling or inhaling to the fullest extent of your lungs. And if you start to cough, knock off the exercises until the cough goes away.