God created the donkey and said to him.
You will be a donkey. You will work un-tiringly from sunrise to sunset carrying burdens on your back. You will eat grass, you will have no intelligence and you will live 50 years.
The donkey answered:
I will be a donkey, but to live 50years is much. Give me only 20years
God granted his wish.

God created the dog and said to him:
You will guard the house of man. You will be his best Friend.
You will eat the scraps that he gives you and you will live 30years.
You will be a dog.
The dog answered:
Sir, to live 30years is too much give me only 15years.
God granted his wish.

God created the monkey and said to him:
You will be a monkey. You will swing from branch to branch doing tricks.
You will be amusing and you will live
20 years.
The monkey answered:
To live 20years is too much, give me only 10years.
God granted his wish.

Finally God created man...and said to him:
You will be man, the only rational creature on the face of the earth.
You will use your intelligence to become master over all the animals..
You will dominate the world and you will live 20years.
Man responded:
Sir, I will be a man but to live only
20 years is very little,
give me the 30years that the donkey refused,
the 15years that the dog did not want and
the 10years the monkey refused.
God granted man's wish

And since then, man lives
20 years as a man,
marries and spends
30 years like a donkey,
working and carrying all the burdens on his back.
Then when his children are grown,
he lives 15years like a dog taking care of the house and eating whatever is given to him,
so that when he is old,
he can retire and live 10years like a monkey,
going from house to house and from one so or
daughter to another doing tricks to amuse his grandchildren.

That's Life.