Let me tell you first WHY Hindu texts are not THAT "specific" like the Holy Books of Abhrahamic religions. Why they usually just tell about the the different spiritual states, and leave up to the seeker, to trace HIS OWN path from one state to other (and eventually to the Absolute). Actually this is common in every aspect of Hinduism. And the reason is because there are ALWAYS innumerable paths between any two states, to be specific. Similarly, there are innumerable paths leading to self-realization, of the God in self.
Anyway now lets jump to answering your question.
The phrase "work without sense", means you should not "react" to the temptations and desires, forced upon you by your sense organs. Senses can ONLY react, on their objects of attachments i.e either in present, or in memory of past, or in imagination of future. That reaction, passing through your "Logical and Intelligent" Brain, and tends to gain complete control of your conscious mind, making you driven by chaos, a creator of "spiritual entropy".
Desires are like a grand ships, in the ocean of mind, ready to sail on the voyage of self gratification, burning the fuel of "your" will. BUT the point here is that those ships itself are, actually made of ICE. Their destiny is to melt back into mind eventually. But till then you would be occupied wasting time in increasing the "Spiritual Entropy" of your system. So its better not to let your mind "freeze", so that the "ships" of desires can melt, as early as possible.
Whatever that tends to completely occupy your consciousness and making you to forget your divine self is a "Sinful" activity. All spiritual-chaos generating, states of mind i.e Kaama, Krodha, Lobha, Moha, Madd, and Matsarya, have the same tendency to occupy the mind. ONLY these "enemies" have the power to generate ARMY of desires attacking your mind.
- SO any Karma done to quench any such desires INSIDE our own self is Vikarma.
- Any Karma done to quench SIMILAR desires in other being i.e OUTSIDE our own self is ("Good") Karam.
- And doing Karma, by keeping Dharma as guide is Akarma. You are not here to quench your thirst OR even the thirst of others, but to REALIZE that the "thirst" itself is a delusion.
At last please NOTE that that worrying too much about Sin, Virtue, Heaven or Hell, "good", "bad", is a trait of Abrahamic religions. Hindu stress more on his own Dharma, rather than on Karma or Vikarma. Because free will ("to apply outside"), is the BIGGEST delusion of this Dukkhalaya Ashashvatt Sansaar. A Hindu knows that if he is always with his higher self and Dharma, everything will fall into place automatically on its own.
NOTE: I seldom provide references when I present my views on the subject, because I think looking up to a book every time you "think!", is a again NOT a hindu trait. Vedas were in souls of ancient sages, they did not mug it up either. Reading Vedas should be a journey of Mind to soul, rather than of memory from one synapse to the other.
Mind you, that there is a difference between Vedas and books of other religion. "Vedas" are NOT "Holy" as in "Holy Bible" or "Holy Quran", but they can for sure MAKE YOU HOLY.