This question can be answered in many different ways. Setting aside science, religion and many other ways life is defined by people. Here is an interesting way to answer this:
We have billions of choices surrounding us every second. These choices exist even when we might not realize it, they’re there.
From billions of choices, we constantly make conscious and subconscious decisions every second, even if we do not realize we are making a decision.
Once our decisions are made, they immediately turn into memories, even if we do not realize it.
We constantly shape our life from billions of choices, which turn to decisions, which turn to memories.
From this, we can define our life as three very important attributes:
Knowing this should make it interesting for us to understand all of the choices we have when making a decision, realizing right after, we get to remember it for the rest of our life.