The way I define life
There are certain things in life that we all know to be true, but we always keep them out of our equations. And that's what makes life complex when it's pretty simple to perceive.
Most of the dictionary quotes the same thing that life is the condition that distinguishes animals and plants from inorganic matter. But I think this equational approach works better for me. Life = Time + Choices. It's simple, fluent, and goes with the biological approach too. Inorganic matters can't make choices.
Now, if you look at the equation, as we can't control time, that leaves us only with "choices". And, that's the simplest way to answer life. It's the choices that can truly represent us.
For example, I can try to learn about the Big Bang in my spare time and ask what happened before that, or I can leave it to the scientists. I can waste the resources I'm blessed with, or I can be minimalist. I can keep judging religions and racism or try to see what makes them believe and where did they get it wrong.
You see, it's the ignorance that makes us unhappy. If we can keep making good choices with our time, happiness will be just a byproduct.
And remember, it's the blessing of the proper knowledge or Hedayat that will make us satisfied in the end. Stay curious, keep exploring, make choices, and learn from them.