People are under greater pressure than before. Nearly 80% of people are suffering from moderate to high levels of mental distress. They have difficulty regulating and suppressing emotions, but they cannot express emotions correctly. To encourage people to develop the habit of tracking emotions, we designed Lemon Moody to use lemon juice as a mentality metaphor to turn difficult situations into good opportunities. When life gives you sour lemons, it means that you will inevitably encounter difficulties in life, but you can turn these sour lemons into sweet lemon juice. We could develop a positive way of thinking by transforming unhappiness into possibilities in life. Squeezing the pressure ball corresponds to the action of squeezing lemon juice. The act of squeezing is a good way to relieve stress and vent emotions to a certain extent. Our design purpose is to help young people understand their mental health status, self-regulate and manage emotions to prevent depression. We found that Cognitive Behavioural Therapy (CBT) is very suitable to help users recognize distorted cognition, reflect on distorted cognition, and face life with a more positive way of thinking.