Life is a..What not?

Life is a limited offer;
No one is an exception to death!
Life is an open opportunity;
All you earn is all you worked for!
Life is a competition;
Birth starts it and death ends it!
Life is a battle,
Both with the world and within!
Life is a gift,
Smile discovers & sadness dishonors!
Life is a challenge,
Courage faces & ignorance loses!
Life is a dream;
More you sleep, quicker it ends!
Life is a song;
Your tune decides its melody!
Life is a diary;
Only you decide what goes into it!