I'm going to post some song lyrics so that I don't have to make any real effort.
The only guarantee in life - 'Guarantees' by Atmosphere.
Is a life worth dying for
Cause death don't wait for no-one
Sittin' on your front door
Edit: Actually, in response to "leaving your mark on the world", that old poem:
I met a traveller from an antique land - 'Ozymandias' by Percy Shelley.
Who said: Two vast and trunkless legs of stone
Stand in the desart. Near them, on the sand,
Half sunk, a shattered visage lies, whose frown,
And wrinkled lip, and sneer of cold command,
Tell that its sculptor well those passions read
Which yet survive, stamped on these lifeless things,
The hand that mocked them and the heart that fed:
And on the pedestal these words appear:
"My name is Ozymandias, king of kings:
Look on my works, ye Mighty, and despair!"
Nothing beside remains. Round the decay
Of that colossal wreck, boundless and bare
The lone and level sands stretch far away.