In both parshiyos, the Tochachos are very long, whereas the Berachos are, in contrast, quite brief. Why the disparity? Is upholding the Torah not as deserving of reward as violating the Torah is worthy of punishment?
In introducing the Tochachah of Parshas Bechukosai, Targum Yonasan ben Uziel interprets the phrase “v’lo sa’asu” – “and (if) you do not perform (all of these mitzvos)” (Vayikra 26:14) as “v’lo ta’abdun min re’us’chon” – “and (if) you do not perform (all of these mitzvos) with positive will and a desirous soul”. (Targum Yonasan ibid.) This indicates that a person’s attitude is a critical factor in application of the Berachos and Tochachos. So, too, we read in the second Tochachah that punishment would come “because you did not serve Hashem your God in joy and good heartedness…” (Devarim 28:47)
Perhaps the Torah is telling us not only that the Jew must serve God with dynamic motivation and love. This is true, but there is more.
When one serves Hashem with love rather than by rote, and by motivation rather than by compulsion, Hashem is a major part of that person’s life. Such a person has a relationship with Hashem; he walks and lives with God. That person’s existence is elevated to a different sphere, such that everything in his life has divine meaning, and he perceives his time in this world as part of a higher calling.
For such an individual, living with Hashem, having a life of kedushah, being part of something higher, is itself the greatest reward. This is perhaps why the Torah does not dedicate dozens of pesukim to the bounty of rewards granted to one who cleaves to Hashem, as the life of him who cleaves to Hashem is already saturated with goodness, which far surpasses worldly rewards.
In this light we can better understand the famous words of Rashi (on Vayikra 26:3, from Toras Kohanim 26:2) that “Im bechukosai teileichu” (“If you will walk in my commandments”) is to be interpreted to mean “She-tihyu ameilim ba-Torah” – “that you must toil in Torah”. The Berachos at the commencement of Parshas Bechukosai are promised to those who toil and immerse themselves in Torah study. One who is engulfed by the holiness of learning Torah is on a different plane; the spiritual surrounds him as the Divine wisdom and vivifying concepts of Torah permeate his mind, such that he goes through life on an elevated existence. This person is more than content with his lot and feels that he has it all, so long as his physical needs are tended to; he does not require dozens of pesukim of Berachos, as his life is already enriched with highest meaning and spirituality.