Take a cold shower.

For a couple of months during the summer, I'd turned to taking cold showers. In July, I started swimming in the mornings before going to work. The rinsing shower at the outdoor pool uses cold water, although the pool water is pretty warm. I quickly realized how refreshing cool showers are on a warm day, and made the decision to turn off my hot water at home. So, while the weather was good enough over about 1.5 - 2 months time, I was only taking showers with un-warmed water. By "un-warmed water", I mean that I wasn't using water from the cold pipe, but water that's been sitting in my hot water tank (that I turned off) for the day.

So, my method of showering would be to start from the legs to get the body used to the temperature, up to the thighs, and then to the torso and head. Work better than standing under the shower head and pressing Go.

After a while, I found I didn't even like hot showers - although warm showers I could bare.

The weather has gotten cooler now (somehow even 23 degrees seems rather cool now), and I've gone back to taking warmer showers. But I would encourage anyone to try out cool showers (or at least to reduce the temperature of their shower water).

Give it a try.