"And the L·rd spoke to Moses, saying: Speak to the children of Israel, that they take for Me an offering; of every man whose heart prompts him, you shall take My offering." (Ex. 25:1-2)

A person should seek ways to transform his mundane desires all that "his heart prompts him" into good qualities. From his habitual, bad traits, he should learn how to serve the Creator with the same passion and desire, even more intensely.
[Tiferet Shlomo, Toldot]

I heard from my Master [the Baal Shem Tov], in the name of Rabbi Sa'adiah Gaon, that it is appropriate to desire all kinds of material things, and through this, to come to a desire for Torah and serving G·d.
[Ben Porat Yosef, Vayechi, p. 85b]
...the boy failed to grasp even a single area of knowledge.
I heard a parable from my Master. A king had a son whom he wanted to teach the various subjects that were required for a prince to know. He hired several scholars, but the boy failed to grasp even a single area of knowledge. The king finally gave up on him, and only one sage remained. One day, the king's son saw a beautiful, young woman, and desired her. The sage complained about this to the king, but the king replied that since the boy shows some desire, even a physical one, it is possible for him to learn all the fields of knowledge. The king ordered that the young woman be brought to the palace, where he told her that she must not listen to the prince's solicitations, unless he agrees to master one branch of knowledge. Afterwards, she should demand that he learn yet another branch. This continued until he mastered all the areas of study. But when he finally became a wise man, he rejected the young woman and married a princess, as was fitting for him.

The meaning of the parable is obvious.
[Ben Porat Yosef, Vayechi, p. 88a]

Translation and Commentary from Sefer Baal Shem Tov by Rabbi Dr. Eliezer Shore; first posted on //baalshemtov.com