The secret of karma yoga is to combine deep interest with perfect detachment. If work is performed for work's sake, if such work is performed for the sake of the commonweal, in a spirit of sacrifice, then you will enjoy an ineffable peace, a bliss that surpasseth all understanding, all description. The gates of the kingdom of God will be thrown open to you. That is what the Lord assures us in the Bhagavad Gita.
Selfless actions are not soulless actions. Put your heart and soul into all that you do. Live in the Lord, and realize that you are an instrument of his will. Whatever is done without this realization is an act performed in ignorance, is an act that would bind you faster to the wheel of samsara (cycle of birth and death).
Three things are necessary when you practice karma yoga. You must be free from egoism; you must not expect any appreciation for the work that you do; and you must have a balanced state of mind in success and failure.
Believe in yourself. Have faith, and know that nothing is impossible to attain for a true aspirant.