These memorable words are from Bill Bryson's A short history of nearly everything:
It is easy to overlook this thought that life just is. As humans we are inclined to feel that life must have a point. We have plans and aspirations and desires. We want to take constant advantage of all the intoxicating existence we've been endowed with. But what's life to a lichen? Yet its impulse to exist, to be, is every bit as strong as ours-arguably even stronger. If I were told that I had to spend decades being a furry growth on a rock in the woods, I believe I would lose the will to go on. Lichens don't. Like virtually all living things, they will suffer any hardship, endure any insult, for a moment's additional existence. Life, in short, just wants to be. But-and here's an interesting point-for the most part it doesn't want to be much. [Bold emphasis added].
As I recall, in that chapter, Bryson gives many examples of organisms -- life -- that exist and thrive in unthinkable environments: hot, cold, acidic, dark, etc. The Scientific American website has a story about a recent discovery of an extremophile species:
... Based on genetic analysis, [this extremophile] appears to be a type of archaea—a single-celled organism similar to but distinct from bacteria.
The microbe lives about a mile below the ocean floor, in temperatures ranging between 140 to 212 degrees Fahrenheit. There they munch on methane and other hydrocarbons. They thus beat all previous sub-seafloor-life records for extreme conditions—twice as deep, twice as hot, and in sediment three times as ancient, more than 110 million years old. ...