Tanya Chapter 44 part 5. Passionate, fiery love comes from realizing the vast distance

We are gifted with love as an inheritance: to realize that Hashem is truly my Life, to realize that Hashem is truly my Father. But just because it's innate doesn't mean it is automatic –– it takes effort on our part. That effort brings these loves to a space of "the heart's desire," and  brings the Torah and mitzvot produced by their motivation to a higher place than instinct, to the world of intellect, the world of Beriah. These loves encompass elements of instinct, intellect, and Divine gift. So, why should we work hard to cultivate intellectual love from the ground up? Because it ignites the flames of passion, and, moreover, it constitutes the very purpose of Man.