Early effort is the absolute requirement for future success, and the degree of preparation dictates the final result. This truth is vividly illustrated through the agricultural cycle, contrasting the necessary labor of farming with a lazy individual who prefers temporary comfort over hard work. During the cold winter months, the lazy person shrinks from the chill and sits idle rather than plowing his land [אבן עזרא]. Consequently, when the harvest season arrives, he is forced to beg for grain from those who put in the effort. However, his pleas go unanswered, and he is left completely empty-handed [מצודת דוד, ביאור שטיינזלץ, עמנואל הרומי].
Beyond the physical farm, this agricultural cycle serves as a profound metaphor for a person's inner spiritual and psychological state. The focus specifically on plowing rather than just sowing is highly significant. Plowing represents the essential preparation of the ground. If a person tries to sow good deeds and Commandments without first plowing the soil of his soul and clearing it of past wrongs, it is as if he is planting seeds directly onto thorns. When the time comes that he desperately needs his spiritual merits, he will discover that they never properly took root and cannot support him [אלשיך].
A primary approach among commentators applies this metaphor directly to the stages of human life. In this view, winter symbolizes the days of youth. This is the critical time to prepare both body and mind, to uproot the thorns of physical desires, and to plant the seeds of wisdom and morality. A young person who acts lazily and gives in to his urges will eventually reach old age, which represents the harvest. At that point, he will want to reap the benefits of a wise life, only to find his mind completely bare [רלב״ג, מלבי״ם]. This reality applies just as much to material matters; someone who avoids the hard work of building wealth during his youth will find himself without any means to support himself in his later years [עמנואל הרומי].
On the highest level, this dynamic mirrors the relationship between our current existence and the World to Come. This world is the winter. It is the realm of action and the only window of opportunity available to study Torah and fulfill God's Commandments. The harvest represents the end of life and the transition to the world of souls, a state of existence that is entirely like the Sabbath. A person who is lazy in his service to God because he is too busy chasing physical desires will eventually seek his reward. He will want to delight in the World to Come alongside the perfected souls, but he will find his hands empty. The spiritual rule is clear: one who does not put in the hard work before the Sabbath will have absolutely nothing to eat when the day of rest arrives [רש״י, מלבי״ם, עמנואל הרומי].