V'Etchanan - What does it mean to love God?

with all your heart: Heb. בְּכָל-לְבָבְךָ [The double “veth” in לְבָבְךָ, instead of the usual form לִבְּךָ, suggests:] Love Him with your two inclinations [the good and the evil]. (Sifrei; Ber. 54a) Another explanation; “with all your heart,” is that your heart should not be divided [i.e., at variance] with the Omnipresent (Sifrei).

ובכל נפשך, according to the plain meaning of the text “even if it will cost your life.” It must mean this: seeing that the Torah had already covered all the other bases when it wrote בכל ללבך, “with all your heart,” the meaning is that while alive you are to love God with all your heart, if your faith and love for God is put to the test and you must choose that or your very survival, you must choose the former.

and with all your means: Heb. וּבְכָל-מְאֹדֶךָ, with all your possessions. There are people whose possessions are more precious to them than their own bodies. Therefore, it says, “and with all your means.” (Sifrei) Another explanation of וּבְכָל-מְאֹדֶךָ is: You shall love God with whatever measure (מִדָּה) He metes out to you, whether it be the measure of good or the measure of retribution.