They pique awareness, double days, likely the 'reason' for their existence. 'Reason' in the most effective sense of being grouped with body and spirit as well as mind.
Had a double day yesterday.
Started out with a phrase being repeated on the radio, no explanation, just a complete repeat.
Second nudge was the walking by for a second time within ten minutes of a regular passerby, I assume on his way to work, as I had my usual tea and bagel on the patio of a neighbourhood deli. He'd gotten on a bus and passed me thusly. Then, a few minutes later, he was walking by exactly as he had first time. Must have gotten off at a stop and gone back home for something forgotten and then started his day again.
Third was catching sight of a man I have not seen in years who bears a most unusual name. A day earlier I had learned that a friend had named her baby this name.
Fourth was having a lady at my knitting Guild suddenly pull a doll from her basket with the intention of asking if anyone had any doll clothes patterns. The doll is most unusual with a real expression of emotion on its face. A "hey!" A "just a minute, here!" I'd never seen anything like this before and had 'chanced' on the exact same doll at a sale a week or so earlier, it spoke to me, I had to have it. And its 'double' had leaped out of a basket
After these I became more alert to further 'doubles' but they are not something you look for, they are the sort of things that happen and present to awareness. A subtle but important difference. And the acceptance that the point to be taken is simply to be aware, to 'check in' as often as possible. To inhabit the body.