Free from attachments, without ego, filled with heart-bred pious intent and enthusiasm, indifferent to success and failure, such a doer is said to be Satwik.
They do what is needed for the good of mankind and live Dharma in their deeds, unaffected by any kinds of favours and biases.

Those seeking sense gratification, inebriated by the results of actions, desirous and greedy, with violent tendencies, jealous and impure (blinded by attachment), overwhelmed by pleasure or grief (by loss or gain) – such doers are Rajasik as known in the world.
Excessively celebrating, exhilarating and any such act that gives adrenalin rush is rajasik. It may throw people out of control sometimes.

Employing illegitimate ways, materialist, impudent, ignoble, expert in sullying the good works, lazy, grouchy and sluggish – such a doer is declared to be Tamasik.
For selfish wants they care not, blinded and emotionally carried away they act in extremes, hurting others.
Srimad Bhagwad Gita’s message is “Enact your duty detached, altruistically, considering benevolent objectivity as duty and expect nothing in return. One should not be overwhelmed by the adverse or desired results.”