In the passage above in John, Jesus talks about seed, as he does in other parables about bearing fruit for God's kingdom. But here, Jesus doesn't just talk about having soil which is free of weeds that choke the seedlings, meaning a life free of distractions. He speaks about the seed itself needing to die in order to multiply and bear fruit. He is saying that one needs to die to one's own most basic desires in order to live for him and receive life that endures for eternity.

In reading this parable, it helps to understand the expectations of a disciple, and how Jesus was thinking of these in this saying. A disciple was supposed to show utter dedication to his rabbi - acting as his "servant" and following him everywhere he taught. To do this one had to embrace a lifestyle of traveling, lack of comfort and sleep, as well as rigorous study of the Torah and the rabbi's interpretation of it. Some quotes about it include,

This is the way [to acquire knowledge] of the Torah: eat bread with salt, drink water by measure, sleep on the ground, live a painful existence, and labor [studying] the Torah.¹

The words of Torah are not retained by one who is lazy regarding them, and not by those who study surrounded by luxuries, food, and drink; but rather by one who 'kills himself' over them, denying himself physical indulgences; one who does not allow his eyes to sleep nor his eyelids to slumber. ²

Other rabbis expected their students to "kill themselves" in their studies in their desire to learn the Bible. How much more should Jesus, our rabbi and Lord, be able to expect from us that we sacrifice our time and lives to learning his words, and living by them too.

¹ As quoted in New Light on the Difficult Words of Jesus, by David Bivin, p 25.

² Maimonides, Hilchos Talmud Torah 3:12. (Commenting on Shabbos 83b, B. Talmud.)