Swamiji Nityanand explians, that in the fast-paced world of today, Kriya Yoga is highly scientific and true like mathematics. “Householders can practice Kriya yoga meditation easily and get rid of all types of stresses, mental worries and ailments while at the same time realize God,” he said.
Swamiji explained that Kriya Yoga was a simple physiological method which created a chain reaction in the body. “It charges our body with abundant amount of oxygen needed for the brain and trillions of cells and tissues constituting our body. During its practice, lungs get filled with extra pure oxygen thereby decarbonising the blood more quickly and efficiently. It reduces the fatigue on the heart, which needs reduced labour to be done to pump the blood through the lungs because of the reduced amount of impurities in the blood,” he said.
of course a Swamiji would say that Kriya Yoga can be easily practiced and is a simple physiological method. For them, it is easy and simple, not necessarily so for the ordinary person ! 
just my humble opinion
