Some ways to meet new friends as an adult are to join clubs and organizations that meet on a regular basis or to join a gym. Adults that enthusiastically engage in activities they enjoy set themselves up to meet others that enjoy the same activities.
Joining a group or club with regular meetings builds the consistency of engaging with people on a repetitive basis. This repeated interaction can lead to new friends. Groups might include a book club, a networking organization or a class. To help make long-term friends through participation in the group, members should engage in social occasions outside formal group meetings.
Likewise, a gym is a place that a person can go on a regular basis to meet new people that become friends. A person at a gym has a good chance of running into someone with a similar interest in fitness.