"Kept on truckin'" is a colloquial expression that means to continue with determination, perseverance, and endurance. The antonyms of this phrase could be words like quit, surrender, give up, back down, or retreat. When somebody quits, they give up and refuse to continue doing something. Surrendering means accepting defeat and giving up control. Giving up means to abandon your goal, and back down means to withdraw from a confrontation. And retreating means to move back or withdraw from a challenging situation. These words signify the opposite of "keep on truckin'," which is to persist and persevere until you reach your goals.