Now, typically we would interpret heart, might, mind, and strength as four separate but interrelated factors that are required in the service of God. May I suggest an additional interpretation? Please consider the word “might” as descriptive of the “heart.” In other words, a mighty heart is required for serving God. Now also consider that the word “strength” as descriptive of the “mind.” Therefore, to effectively serve God we also must have a strong mind.
Perhaps, then, another way of interpreting this verse is as follows: O ye that embark in the service of God, see that ye serve him with a mighty heart, and with a strong mind, that ye may stand blameless before God at the last day. The mighty heart equates to the faithfulness and spiritual strength.... And the strong mind equates to competence achieved through intellectual diligence and discipline.
(BYU-I Devotional Address, "Your Whole
Souls as an Offering Unto Him," Jan 5, 1999)