tried cold water swimming, twice

My neighbour has been going to the lido every Saturday for months and eventually I ran out of reasons not to join her. Went twice now. The first time I was in for about four minutes and felt completely alert for the rest of the morning, which was useful because I had a full day with the kids and no patience to spare. The second time the water was colder and I lasted about the same, but the alertness did not follow in the same way. My anxiety did feel quieter both afternoons, though I cannot say whether that was the cold or just two hours away from the house. I am not converting to anything. It is just a thing I am doing on Saturdays for now.