If you will walk in My statutes and observe My commandments and perform them; then I will provide your rains in their time, and the land will give its produce and the tree of the field will give its fruit (Vayikra 26/3).
Rashi comments on "IF YOU WILL WALK IN MY STATUTES"-On might be able to think that this refers to fulfillment of the commandments. When it says "and observe My commandments"- "and perform them"---we see that the fulfillment of commandments have been stated.
What, then is meant by "if you will walk in My statutes"?-- that you should toil in Torah.
The Rebbe of Ozerov asks the following question; We find that Chazal say the following; (Torath Kohanim on this posuk) "we learn [from this parasha] that Hakodosh Boruch Hu lusts after the toil of Yisroel in Torah".
So, therefore we must ask, the command of studying Torah is merely only one out of the total 613 mitzvot, as its written "you should teach (Torah) to your offspring"(Devarim 6/7). In Kiddushin 30/1, it says that we learn from this posuk, that the words of Torah should be always on the tip of your tongue (heb.sharp in your mouth) so that if someone asks you something in Torah you will not stammer but answer immediately.
Therefore, its apparent that this command of laboring in Torah is already included in the words "and observe My commandments", that immediately follows "If you will walk in My statutes", which makes it completely superfulous.
The Maharal (Gur Aryeh) explains how Chazal understood from here that to walk in My statutes implies--toiling in Torah,because the Torah used the expression "to walk", instead of the more appropriate word which is "study the statutes". Since the term walking implies toil and work, likewise one should work and labor in Torah.
He also offers another interpetation to this drasha; The study of Torah should emulate the act of walking and traveling, where each step brings us closer to our destination. Likewise we should'nt be satisfied with a superficial understanding of Torah, but we should constantly continue walking even more deeply to penetrate the depths of Torah.
The Midrash Raba comments on the posuk (Mishlei 24/70)"Wisdom is a rare jewel in the eyes of the fool, he is silent in the portals". The Rabbonim say, the fool enters the halls of study and sees everyone preoccupied with the study of Torah. He asks, "how does one attain proficiency in the knowledge of Torah? They reply ; first you begin with learning the letters of the aleph-bet,and afterwards reading words. The next stage you study Tanach. When you are proficient in Tanach, you continue on to Talmud etc. etc. After hearing this, the fool thinks in his heart, how is it possible to accomplish all this? [Discouraged] he exits the portals [of the halls of study].
From this Midrash we see that the real toil and labor of Torah is wholehearted commitment to a life of constantly and steadily adding to our store of knowledge and understanding of Torah. without any letup.