Bereft of desires, with sufficient restraint over mind and senses, eschewing all kinds of gifts or gains, doing only bodily (physical) activities, one will not incur sin at all.
There is no question of incurring any blemish whatever, if one is without desire and greed. He should also not be interested in any kind of gifts or personal gains.
Activity as such is not undesirable or painful. It is the wrong notions about activity and consequent responses from the mind that cause trouble and torment. Right understanding alone is the solution for any plight.
One has to reflect upon the plight deeply. Life is interactional. Interactions will result in sukha-duhkhas, the indispensable two. None has to strive for them (2.14).
No result is then ever new or different. All objective outcomes together can produce sukha or duhkha alone. This discrimination is greatly relaxing and makes one poised and pleasant throughout! The gain and the skill in performance it bestows are quite substantial.