Emperor Hadrian saw an old man cutting down shrubs in order to plant saplings. He said to him,
‘Old man! What is your age?’
He answered, ‘One hundred.’
‘You are 100 years old and you stand here cutting down trees in order to plant saplings? Do you think you will eat of their fruits?’
He replied, ‘If I am worthy, I shall eat. If not, just as my parents toiled for me, so shall I toil for my children.’
Kohelet Rabbah (via rac.org)