"When you shall come to the land and you shall plant any food tree." (Levit. 19:23)

The Holy One, blessed be He said to Israel that even though you will find the land full with all that is good, you should not say, "We will sit and NOT plant." Rather you must be careful to plant as it says, "you shall plant any food tree." Just as when you entered the land and found plants that others had planted, so too shall you plant for your descendants. (Midrash Tanchuma, Kedoshim ch. 8)

If he merits he will gain the benefits, and if not, others will get the benefits.

One should never say that he is too old, how much longer will he live, and why should he get up and get tired for others since he is soon to die. King Solomon said, "He made everything beautiful in its time. He also put the world into their heart.". (Eccl. 3:11) The word for 'the world/ha’olam', is written without [the usual] Vav, spelling he'elam," meaning "the concealment." Why? For if the Holy One, blessed be He, had not hidden from man's heart the thought of his imminent death, he would never build nor plant, for he would say that tomorrow he would die, so why should he get up and get tired for others. Therefore the Holy One, blessed be He, hid the death day from the heart of man so that he would build and plant. If he merits he will gain the benefits, and if not, others will get the benefits.

There is a story about Adriyonus Caesar who was going to war and marching with his soldiers to fight against a rebel area. He found an old man who was planting fig trees along the way. Adriyonus asked him, "You are an elderly man, so why are you standing and working and tiring yourself for others?"

He answered, "My master the king, I am planting now and if I merit I will eat from the fruits of my planting. But if not, then my children will eat."

Adriyonus was at war for 3 years and he then found the same old man in the same place. What did the old man do? He took a basket and filled it with the beautiful first-to-ripen figs and gave it to Adriyonus, saying, "My master the king, please receive this from your servant. I am the old man whom you found on your way three years ago and you said to me, ‘You are an old man, so why bother yourself and exhaust yourself working for others?’ However the Omnipresent One has permitted me to eat from the fruit of my plantings. These that are in the basket are a present from me."

Right away Adriyonus told his servants to take the basket from him and to fill it with gold coins. And so they did.

[From "Etz Hayyim Hee – Supplement", page 3-4.