All of the animals except for man know that the principle business of life is to enjoy it.
How well said! We and tend to live life by years and not in moments. Life is not all living a lifetime, the essence lies in living a lifetime in each moment. Enjoy each day to the fullest. It is often said that live each day as if it were your last. I say, live each day as if it were your whole life. This might prove to be a more positive approach towards life in general.
If we consider death as the end of life, we are being apprehensive towards the inevitable future. But if we enjoy the bliss of life in breathing in a lungful of fresh air free of any smoke etc., if we find extreme joy in the chirpings and twitterings in morning fresh breeze, if we can spread cheer around, if we can make at least one crying person smile, if we can do justice to the deserving being deprived of the things that the undeserving have in plenty, if we can laugh at the joke which targets us, if we can just be ourselves at all times, if we don't exhibit a poker-faced personality....then we can say we are living in the real sense of the term. Otherwise we'll be merely existing!!!
So better wake up and start living...stop existing!