The article claims that having hobbies can increase your happiness and decrease stress. They claim, "Spending time on an activity that you enjoy can improve your mental health and wellbeing. In fact, people with hobbies may be less likely to experience stress, low mood, and depression." Additionally, according to Harvard Health Publishing, "The study is observational and doesn't prove that hobbies caused people to be healthy and happy. But the researchers say hobbies — such as arts and crafts, games, gardening, volunteering, or participating in clubs — involve creativity, sensory engagement, self-expression, relaxation, and cognitive stimulation, which are linked to good mental health and well-being. Plus, taking part in hobby groups keeps you socially connected, which helps reduce loneliness and isolation." Based on these two sources, it seems that having hobbies doesn't necessarily cause happiness, but it is a variable for developing better mental health and well-being. Doing something you enjoy can take your mind off of anxious or depressing thoughts, and can connect you to people who also enjoy similar activities. In addition to the previous sources, Birch Psychology also claims, "Having a hobby along these lines boosts our self-esteem, as we feel good at something, and give us the “success” hormones of dopamine, serotonin, oxytocin, and endorphins, which make us happier. They reduce our stress, give us a sense of purpose, and give us pride." According to them, having a hobby that ends with a created product can increase hormones that make us feel good.
https://www.headtohealth.gov.au/living-well/purposeful-activity#:~:text=Spending%20time%20on%20an%20activity,feel%20happier%20and%20more%20relaxed.
https://www.health.harvard.edu/mind-and-mood/having-a-hobby-tied-to-happiness-and-well-being
https://www.birchpsychology.com/birchs-blog/2023/4/30/hobbies-for-happiness