What do you mean by “concentration”?
Concentration is the open secret of focusing all one's attention on a particular object or person in order to enter into and have one's identification with that object or person. The final stage of concentration is to discover and reveal the hidden ultimate Truth in the object of concentration. What concentration can do in our day-to-day life is unimaginable.
What is the best point we can use to fix our gaze for concentration?/
It depends on the individual. Some people find it easier to look at the flame of a candle and concentrate, while others find it easier to look at a beautiful flower. Still others prefer to look at the rising sun and concentrate. So if the individual gets a kind of inner joy when concentrating on a particular object, he should concentrate on that object in order to achieve his goal.
Concentration can be done at any moment, at any place, in any position; it need not be done only while sitting. When the inner being compels us to concentrate, we concentrate. There is no hard and fast rule that one has to concentrate only while standing or while seated in the lotus position. When the inner being inspires us, we aspire, and this aspiration can be expressed either in the form of concentration or meditation.