IT WAS Owen Murphy who posed the question in a tweet. "You're in my prayers" he could understand, but what does it mean when people say, "You're in my thoughts?" Is this just a limp prayer-lite?

I was pondering this recently when Anna Wardley, a 37-year-old from Hampshire, went for a swim. She was attempting to swim round the Isle of Wight - 60 miles of water. "It's been nearly 30 years since this challenge was successfully completed," she said; "so I'm under no illusions."

And why would she be? Although she is an experienced long-distance swimmer, in August she had to abandon her attempt to swim around the Isle of Tiree, in the Inner Hebrides, when she began hallucinating from the effects of cold water, which left her unable to breathe properly.

Now, faced by the Isle of Wight challenge - a swim reckoned to take about 30 hours - she asked for our thoughts. "There will be a time when I'll be swimming against the tide through the night," she said, "almost on the spot, for hours. However, just knowing people are thinking of me and willing me on will definitely help when the going gets tough."

It would be particularly tough, because, following the rules of the British Long Distance Swimming Association, she would be wearing only a standard swimming costume, goggles, and a swimming cap. It was her against the elements; so no wonder she wanted our thoughts. But do they mean anything?

For part of the time that Anna swam, I was doing a long run, full of difficult hills. It was not comparable to the cold depths around the Isle of Wight, but hard enough. And I noticed that when I was really suffering, and wondering whether I could continue, I was thinking of Anna, 80 miles to the south, but beneath the same sky.

We were somehow in this together, and her example encouraged me. But did Anna feel the benefit in the cold waters?

Card-sellers want us to think of people. As one says on its website: "Think back to times in your life when you received an email, or a note from someone, for no special reason other than that they were thinking about you. It makes you feel good, brings a smile to your face, and helps to make us realise that we are not alone, that others do care."

Thought and prayer are related, but different. A thought is an act of solidarity; prayer, a letting go. A thought is empathy, a springboard for kind action; prayer is acceptance, an act of deep trust.

Anna Wardley completed the swim in 26 hours and 33 minutes. But I can't take all the credit.

Simon Parke is the author of Pippa's Progress: A Pilgrim's Journey to Heaven (DLT, 2012).