The first important step is to master the Asana of posture or to control the body. The next exercise is Pranayama. Correct posture is indispensable requisite for the successful practice of Pranayama. An easy comfortable posture is Asana. That pose is the best which continues to be comfortable for the greatest length of time. Chest, neck, and head must be in one vertical line. You should not bend the body either forwards or laterally, i.e., either on the right or left side. You should not sit crooked. You should not allow the body to collapse. You must not bend the body either forwards or backwards. By regular practice the mastery over the pose will come by itself. Fatty people will find it difficult to practise the Padma Asana or the Lotus Pose or Siddha Asana (perfected pose). You need not wait for practising Pranayama till you get full mastery over the Asana. Practice Asana and side by side you can practise Pranayama also. In course of time, you will acquire perfection in both. Pranayama can also be practised by sitting in the chair erect.
In Bhagavad-Gita, the Immortal Song of Lord Krishna, you will find a beautiful description of seat and pose: "In a pure secret place, all by himself, established in a fixed seat of his own, neither too high nor too low, with cloth, black antelope-skin and Kusa grass one over the other, there, making the mind one-pointed, with thought and the functions of the senses controlled, steady on his seat, he should practise Yoga for the purification of the Self, holding the body, head and neck erect, firm, gazing steadily at the tip of the nose without looking around" (Ch. VI-10, 11 & 12).
Pranayama is the control of the Prana and the vital forces of the body. It is regulation of the breath. This is the most important step. The aim of Pranayama is the control of Prana. Pranayama begins with the regulation of the breath for having control over life-currents or inner vital force. In other words, Pranayama is the perfect control of the life-currents through control of breath. Breath is external manifestation of the gross Prana. A correct habit of breathing must be established by the regular practice of Pranayama. In ordinary worldly persons the breathing is irregular.
If you control the Prana you can completely control all the forces of the Universe, mental and physical. The Yogi can also control the Omnipresent manifesting power out of which all energies take their origin, whether concerning magnetism, electricity, gravitation, cohesion, nerve- currents, vital forces or thought-vibrations, in fact the total forces of the Universe, physical and mental.
If one controls the breath or Prana, the mind also is controlled. he who has controlled his mind has also controlled his breath. If one is suspended, the other is also suspended. If the mind and Prana are both controlled, one gets liberation from the round of births and deaths and attains immortality. There is intimate connection between the mind, Prana and semen. If one controls the seminal energy, the mind and Prana are also controlled. He who has controlled his seminal energy has also controlled his Prana and mind.
He who practises Pranayama will have good appetite, cheerfulness, handsome figure, good strength, courage, enthusiasm, a high standard of health, vigour and vitality and good concentration of mind. Pranayama is quite suitable for the Westerners also. A Yogi measures the span of his life not by the number of years but by the number of his breaths. You can take in a certain amount of energy or Prana from the atmospheric air along with each breath. Vital capacity is the capacity shown by the largest quantity of air a man can inhale after the deepest possible exhalation. A man takes fifteen breaths in a minute. The total number of breaths comes to 21,600 times per day.