As a growing young adult, you probably have wondered how to live a long, successful, and happy life in the future. While it is easy to think that happiness comes from being rich or a similar material achievement, studies are (and have been) saying otherwise.

For example, an iconic 75-year-long Harvard study led by George Vaillant and Sheldon Glueck said that the key to happiness is rather simple.

Social connection, quality over quantity

First, the study revealed that socially connected people to families, friends, and communities are happier, granting them a longer life than less socially connected people. 

Loneliness indeed kills. According to doctors, lonely people are generally less happy and have more health-related problems. They also tend to suffer from sleep disorders and mental health issues. Their brain functions also decline sooner than those who are not lonely. 

However, it doesn't mean that you should go out there and befriend anyone you see. You may have heard this warning from your parents or teacher: quantity over quality. When it comes to healthy social connections, it is not about the number of friends you have. Rather, it's about the quality of their companionship.

Being in a miserable relationship will not make you happier. For instance, a study showed that people who were alone were happier than people influenced by toxic relationships. Although the number of social relationships mattered more to people in their 20s than it did to people in their 30s, it was found that people in their 20s were not happier than people with just a few true friends. 

Closer relationship

Staying connected with people enhances brain health and slows down mental decline. If you're at loss as to whom you should prioritize when it comes to maintaining social connection, then the simple answer is you should first start with your family members, especially since they tend to last for a lifetime (or at least, their lifetime). 

You can maintain your connection with your spouse, partner, parents, or siblings and therefore keep them close simply by investing your time in them. It is also important to note that the study also concluded that harmony in the marriage makes people happier and improves their health, regardless of material wealth. 

Understandably, people might be too occupied by work from time to time, which means it is necessary to purposely set aside such a time. In the modern context, it is important to replace some of your "screen time" with "people time" — a family night out, for instance, or alternatively, you can reach out to a family member you haven't spoken to for years.