Hi João and everyone :)

i borrowed this 'defintion' of life where life is defined through a poem:

       _________ " Living " (Author" Unknown)___________

To touch the cup with eager lips and taste, not drain it;

To woo and tempt and court a bliss -- and not attain it;

To fondle and caress a joy, yet hold it lightly,

Lest it become necessity and cling too tightly;

To watch the sun set in the west without regretting;

To hail its advent in the east -- the night forgetting;

To smother care in happiness and grief in laughter;

To hold the present close -- not questioning hereafter;

To have enough to share -- to know the joy of giving

To thrill with all the sweets of life -- is living.

______________________

The way you live your life is a gift to those who come after (you).

Make it a fantastic one (for them). (it= gift)

What life is is life?

Here are two definitions of life I like.

"Life is a journey between the first and last breath"
"Life is a journey between the womb and the cemetery."

What is your personal definition of life?

Just a tiny little correction to word order in the title! 

As a statement rather than a question, you would phrase it as you had: "What life is."

I hope that was helpful :-)