A traveler through the mountains came upon an elderly gentleman who was busy planting a tiny almond tree. Knowing that almond trees take many years to mature, he commented to the man
"It seems odd that a man of your advanced age would plant such a slow-growing tree!".
The man replied "I like to live my life based on two principles. One is that I will live forever. The other is that this is my last day."
(paraphrased from either Lao Tsu or Chuang-T'su)