The second law of thermodynamics says that "...the world acts spontaneously to minimize potentials..." This universe is constantly moving toward greater and greater disorder. It begs the question of how to understand a Big Bang and evolution without Divine intervention, but that's not my point here.
In simple terms, this law of entropy means that things left alone will disintegrate, fall apart, and eventually disappear. Existence is only extant as long as there is a force supporting its existence.
The same is true of life itself. The normative state of living things is death. We humans are only alive because we are constantly making ourselves live. The body is dying due to lack of oxygen, but we are constantly breathing in oxygen to keep it going. The body is disintegrating, but we are replenishing lost cells every time we eat. The body is being tugged toward Earth by gravity, but we force ourselves to stand and sit upright. We are, in effect, continually pumping life into an inanimate collection of atoms that we call our body.
Life is not simply a state of being; it is a state that we are choosing to perpetuate. And that which is true on a physical level is always mirrored on a spiritual level.
In this week's Torah portion we are told: "Choose life, in order that you may live" (Deut. 30:19). Spiritual life is as much a choice as physical life. Left alone, a person's state will tend toward low moods - depression, selfishness, mindlessness, laziness and similar effortless states. Unless we actively choose to be alive, awake, energized and engaged in life, we will sleepwalk through the world.
We human beings are not naturally interested in being awake and alive spiritually. We must put in an effort to do so. If we wish to be alive, then we must choose life. Rosh Hashana is a time to wake up to life. We have probably been asleep for most of our year. The shofar is an alarm clock, beckoning us to wake up - to wake up and choose life, so that we can truly live.