This video from National Geographic makes many of the points I keep harping about, so I don't have to bother writing another earth day post from scratch.
Thinking holistically and extrinsically, taking shorter showers is fine, but consuming less things that take enormous amounts of water and energy to produce is even better.
Cotton is a notoriously thirsty crop, so consuming one less t-shirt frees up enough drinking water for 900 people for one day. This is not an academic tradeoff. Water is routinely diverted from other uses in food-scarce dry and poor countries to produce cotton, a cash crop sold abroad.
Meat is also high up on the water and energy footprint scale. After some trial and deliberation, we've decided not to go completely meatless, but to enjoy vegetarian meals more often than not. YMMV. But, if each household trimmed back their consumption by 20% (of any good), that's the same impact as if one household in five went cold turkey and the rest did nothing out of the mistaken belief it was an all or nothing proposition.