We've already talked about how taking a lukewarm shower can help your skin look better, since excessive heat leaves your skin dry and cracked (just like leaving your thermostat up too high drains moisture from the air). This is good for your skin and your wallet: lowering the temperature on your water heater can save you as much as 5 percent on your energy bill. And it's good for the earth, since less energy use means fewer resources and a smaller carbon footprint.

But turning up the cold has other benefits, too: it stimulates circulation, making your skin look healthier and younger; it can (weirdly) make you feel warmer for the rest of the day; it's good for your immune system; and a quick blast of cold at the end of a shower is said to keep hair shiny and smooth.

If you're hesitant to jump right into a cool shower, try this slower technique from eHow: start by washing and conditioning your hair, but keep everything beneath your head dry. Then use a washcloth to wash yourself in sections; this will help you get acclimated bit by bit.

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