well there are two issues involved here . One is when one remains for a longer period say more than 15mts. The other like at a flag ceremony is short say 1 to maximum 3 mts.
In the first one meditates , to try and master ones thoughts. The mastering of ones thoughts ahas four stages :
1) Observation of one's thoughts that come in and go of our mind.
2) Surveying of thoughts - god and bad, but no action taken.
3) Control of thoughts - one rejects the bad ones and keeps only the good ones.
4) Mastery of thoughts - One aloows only the good thoughts , the bad ones are rejected even before they enter our mind .
In the second case it is concentration, ie . one pinpoints one's attention like an arrow on any given aim and one penetrates it with the precision of an arrow. Of course with practice one can concentrate even for several hours, but that is rare indeed !
"Every Friday I shall read out to you a few verses of the Dhammapada, then we shall meditate on that text. This is to teach you mental control. If I think it necessary I shall give you an explanation.
The Dhammapada begins with conjugate verses; here is the first one:
In all things the primordial element is mind. Mind predominates. Everything proceeds from mind.
Naturally, this concerns the physical life, there is no question of the universe.
If a man speaks or acts with an evil mind, suffering follows him as the wheel follows the hoof of the bullock that pulls the cart.
That is to say, ordinary human life, such as it is in the present world, is ruled by the mind; therefore the most important thing is to control one's mind; so we shall follow a graded or “conjugate” discipline, to use the Dhammapada's expression, in order to develop and control our minds.
There are four movements which are usually consecutive, but which in the end may be simultaneous: to observe one's thoughts is the first, to watch over one's thoughts is the second, to control one's thoughts is the third and to master one's thoughts is the fourth. To observe, to watch over, to control, to master. All that to get rid of an evil mind, for we are told that the man who acts or speaks with an evil mind is followed by suffering as closely as the wheel follows the hoof of a bullock that ploughs or draws the cart.
This is our first meditation. " --- The Mother