Karma yoga appeals easily to people who are energetic and enterprising, but energy and effort are not enough. There must be no thought of feathering our own nest or of earning profit and prestige, for the moment these thoughts come in, our action is no longer karma yoga.
Easwaran defines Karma Yoga by its psychological requirement — the complete exclusion of self-interested motivation — and treats this as the criterion distinguishing it from ordinary energetic activity.
, The Bhagavad Gita for Daily Living: A Verse-by-Verse Commentary, 1975thesis