Happiness is a state of mind and body as well as brain state. One important tool that impacts more than happiness is to get a lot of bright/sun light early in the day, and avoid it after 10pm. Make your indoor as bright as possible during the day with sun and artificial lighting then lower them at evening. Happiness and other emotions don't correspond to measurable neurochemicals in the brain and body. However, lower/upper baseline levels of dopamine result in lower/upper self-reported levels of happiness. Dopamine and serotonin impact happiness but aren't the only neuro-modulators doing it. Highlights from the Harvard Happiness Project are that income doesn't directly correlate to happiness as it doesn't scale past a certain point (income vs cost of living) even though it buffers stress, having proper social interactions with peer meaning that you have time and money to participate. You are happy when your income allows you to pay for rent, food, and social activities with peers, or at least not stressed. Another finding is that working with meaning brings happiness. Increase your overall well being with deep sleep, quality nutrition, quality social interaction, purposeful work, exercising, and pets to open the door to happiness. Well being criteria change as we age and happiness follows a U shape (+ at 20-25 and 60-65, - between). Self-reported level of happiness is higher childless than with children despite parents saying that their kids is a great source of happiness. The U shape is linked to having children and work thus bringing at lot of responsibilities and stress. After 20 years old, people report less happiness on their birthday as is it the day where they benchmark their life meaning happiness is relative to our peers. Chronic smokers and regular alcohol drinkers have lower levels of happiness, same for people with major trauma as it fundamentally changes how one functions. One study of Dan Gilbert found that lottery winners and paraplegics report a not too different level of happiness 1 year after the event. We have more control on our happiness than we might think thanks to internal synthetic happiness achievable by expecting positive outcomes and framing/eliminating choices for example. Natural happiness is based on things we already enjoy like completing a degree, finding a mate, making a good income, getting a gift. Synthetic happiness is at least as powerful a natural happiness and can be even more powerful. Synthetic happiness requires some effort and situational/environmental conditions. Synthetic happiness is linked to neuro-state of anticipation. Visual and sound effects in a environment gives the brain information on how to process happiness. Make your environment cheerful to have a cheerful mood. Synthetic happiness doesn't mean fake but self-created. Gratitude works if both the giver and receiver are genuinely interested. Giving to others bring more happiness than giving to yourself. Being focused influences happiness positively while a wandering mind is an unhappy one. Quality social interactions/connections (mate, family, friends, colleagues, etc.) is extremely powerful to increase happiness levels, even just seeing friendly faces for a short moment in the early morning and late afternoon. Because mutual eye contact is followed by looking away, attention is constantly ramping up then breaking up. Physical contact/presence is important, even non-sexual/intimate, that's why pets work so well. The core reason behind these positive effects of non-sexual physical socializing (social grooming) is that they stimulate some sensory neurons called C-tactile afferents that are located near the skin and create a feeling of well being and increases oxytocin when touched. It may seem counter-intuitive but having too many choices reduce happiness and making a choice final brings more happiness than being able to change mind. Make a choice, stick to it, forget the alternatives. Thinking about X other alternatives divides dopamine by X. If you are constantly in a mode of evaluative decision making, even after you've made the decision, you are not neurochemically nor psychologically able to extract the feelings of happiness associated with the choice that you made. To conclude, the main components of happiness are the meaning of your social connections and meeting your financial security buffer.
Andrew Huberman