"Looking sunny side" implies being optimistic or hopeful. So, some antonyms for this phrase could be pessimistic, gloomy, cynical, defeatist, negative, or despondent. Such individuals tend to focus on the negative aspects of things, dwelling on failures instead of successes. They might lack faith in the future or in their abilities, feeling overwhelmed by setbacks or challenges. They might also be distrustful of others or doubt the intentions of those trying to help them. Regardless, "looking sunny side" is a much more positive and productive mindset that can lead to greater resilience, creativity, and happiness.