Co-workers create a hostile atmosphere.
Every company, office and job team develops its own work culture. Imagine, for example, an office full of baseball fanatics, where fantasy baseball is the center of conversation in the spring and the World Series is the main topic of conversation in the fall. This kind of connection can help co-workers bond and become a better team, but it can also make the office an exclusive -- and even uninviting -- place for outsiders.
If you're in a work environment where the culture isn't conducive to your productivity, happiness or comfort, consider what's at the root of the discomfort. If it's something generally nonthreatening, such as the group's love of baseball, for example, perhaps you can find other co-workers who share your outsider status. Or perhaps there are other topics that the office could come together over. It could take time, but with enough patience, you may see the office environment shift to focus on more inclusive topics, themes and values.
Sometimes, however, a work environment is rigidly exclusive or is based on unhealthy themes, such as sexual discrimination or the use of drugs and alcohol. If this is the case, you should familiarize yourself with Equal Employment Opportunity (EEO) and anti-harassment laws in your state and country. You may be in a position to stop a culture of illegal discrimination through an EEO complaint.
If the problem is one of simply not being part of the office's culture, however, you may decide it's best to find a new job.