तस्मादोमित्युदाहृत्य यज्ञदानतपःक्रियाः।प्रवर्तन्ते विधानोक्ताः सततं ब्रह्मवादिनाम्॥
tasmād oṃ ity udāhṛtya yajña-dāna-tapaḥ-kriyāḥpravartante vidhānoktāḥ satataṃ brahma-vādinām
Word by word
The verse says
So those who speak of the absolute always begin an offering, a gift or a discipline by saying Om, as the teaching lays down.
In plain words
A word said at the start. That is all this is.
Not a spell. A marker. Oṁ goes at the front of the act the way a name goes on a parcel.
And the point of saying it out loud is that the act is now addressed. Something has been decided before the hands start moving, which is the only moment at which it can be decided.
Where you've felt this · in growing older
Your grandfather says something under his breath before he eats, every time, and has done for sixty years. It takes about two seconds. He is not devout in any way he would describe out loud. When you ask him why, he says that otherwise you are just putting food in your mouth, and he does not elaborate.
Going deeper
Saying something at the start of an act is being described as the moment the act gets its direction, and that is more than ceremony.
An act that begins without being addressed does not stay neutral. It drifts toward whatever you already want, because that is the strongest thing present. A word at the front is a small intervention at the one point where intervention is cheap.
Oṁ works for this precisely because it means nothing in particular. It is assent, not a request. You are not asking for an outcome. You are agreeing to the act before you start, which is what most of our acts never receive.
And the scale of it is the encouraging part. Two seconds, before the meal or the work or the difficult conversation. Not a practice that needs an hour and a quiet room. The whole weight is put on the moment before.