Fix the mind on some object either within the body or without. Keep it there steadily for some time. This is concentration. You will have to practise this daily.
Purify the mind first through the practice of right conduct and then take to the practice of concentration. Concentration without purity of mind is of no avail. There are some occultists who have concentration. But they have no good character; that is the reason why they do not make any progress in the spiritual life.
He who has a steady posture and has purified his nerves and the vital sheath by the constant practice of control of breath will be able to concentrate easily. Concentration will be intense if you remove all distractions. A true celibate who has preserved his energy will have wonderful concentration.
Some foolish, impatient students take to concentration at once without undergoing, in any manner, any preliminary training in ethics. This is a serious blunder. Ethical perfection is a matter of paramount importance.
You can concentrate internally on any of the seven centres of spiritual energy. Attention plays a very prominent part in concentration. He who has developed his powers of attention will have good concentration. A man who is filled with passion and all sorts of fantastic desires can hardly concentrate on any subject or object even for a second. His mind will be jumping like an old monkey.
He who has gained abstraction (withdrawing the senses from the objects) will have good concentration. You will have to march on in the spiritual path step by step and stage by stage. Lay the foundation of right conduct, postures, regulation of breath and abstraction to start with. The superstructure of concentration and meditation will be successful then only.
You should be able to visualise the object of concentration very clearly even in its absence. You will have to call up the mental picture at a moment's notice. If you have concentration you can do this without much difficulty. In the beginning stage of practice, you can concentrate on the 'tic-tic' sound of a watch or on the flame of a candle or any other object that is pleasing to the mind. This is concrete concentration. There is no concentration without something to rest the mind upon. The mind can be fixed on any object in the beginning which is pleasant. It is very difficult to fix the mind, in the beginning, on an object which the mind dislikes.
Sit in lotus-pose (Padmasana) with crossed legs. Fix the gaze on the tip of the nose. This is called the nasal gaze. Do not make any violent effort. Gently look at the tip of the nose. Practise for one minute in the beginning. Gradually increase the time to half an hour or more. This practice steadies the mind. It develops the power of concentration. Even when you walk, you can keep up this practice. Sit on lotus-pose and practise fixing the mind between the two eyebrows. Do this gently for half a minute. Then gradually increase the time to half an hour or more. There must not be the least violence in the practice. This removes tossing of mind and develops concentration. This is known as frontal gaze. The eyes are directed towards the frontal bone of the forehead. You can select either the nasal gaze or the frontal gaze according to your taste, temperament and capacity.
If you want to increase your power of concentration you will have to reduce your worldly activities. You will have to observe the vow of silence every day for two hours or more.
Practise concentration till the mind is well established on the object of concentration. When the mind runs away from the object bring it back again.
When concentration is deep and intense all other senses cannot operate. He who practises concentration for three hours daily will have tremendous psychic power. He will have a strong will-power.