"’Verily I say, men should be anxiously engaged in a good cause, and do many things of their own free will, and bring to pass much righteousness.’ (D&C 58: 26-27.)
“The scriptural contrast between ‘slothful’ and ‘anxiously engaged’ is particularly vivid. The adjective ‘slothful’ is derived from the slow movements of the South American sloth, an odd animal about two feet long that hangs upside down from hooklike claws on tree limbs. It feeds slowly on leaves and buds. The sloth may fall asleep in its upside down position, and can continue to hang in this position for some time after it dies. Scientists say the sloth moves so slowly because of its extremely low body temperature.” (Church News, 04/17/93)
Neal A. Maxwell
"Muttering and murmuring are often the expressions of our conscience gone grumpy; it is precisely because we know we need to respond affirmatively (and have some inkling about what’s coming) that we let off steam—we start puffing in advance of the climb. These are reactions genuinely to be avoided, since they can precede the keeping of a commandment or the fulfilling of a task with a slothful heart, which is more serious.
“Mostly, to avoid muttering, we need to trust more. So many of the things muttered about before turn out to be marvelous experiences later, and we are inwardly, and deservedly, ashamed for having grumbled.” (Deposition of a Disciple, p. 31)