"Self-forgiveness is always critical to helping someone move past whatever secret that is," von Reiche said. She sometimes gives clients take-home exercises -- write down 15 reasons that you forgive yourself, for example.

Lifestyle choices

The skeletons that Rachel keeps in her closet are actually costumes. Tucked away in her studio apartment are a wolf's head and a full leopard outfit.

Rachel, 26, doesn't want her co-workers to know that she's a "furry."

Portrayals in popular culture may suggest the furry movement is about having sex in animal costumes, but for some people that's not part of it at all, she said.

Individuals may define "furry" differently, but in Rachel's view, furry fandom consists of people who enjoy cartooning, fantasy and humanized creatures. It's a way of identifying yourself through animal characteristics, she said, and some furries just appreciate the artwork.

Rachel herself lives in the Midwest and is an artist on the side, drawing humanized animal characters. She particularly identifies with the hyena that she draws a lot.

As much as she enjoys going to furry conventions, she tries to keep that under wraps at work. She's a manager at a Web software company and wants to maintain a certain level of professionalism.

"If people knew I had this whimsical side that likes to dress up and goof off, and that I draw cartoons in my spare time, that might seem kind of off-kilter," she said.

It's important for people to be comfortable and confident with all parts of themselves, McDonald says. But there are situations where revealing part of your identity would do more harm than good.

"It can be unhealthy to reveal certain parts of ourselves if there are people close to us that would be very unaccepting of it, because of the pain and the separation that that would cause to reveal that," McDonald said.

Affairs

"My biggest regret is that I ever started cheating on my husband," says a post on the Secret Regrets site. "Every time I do it, I say it's the last time, but it never is. I don't know how to stop, and I feel so guilty about it."

It's a secret that psychologists often hear -- that someone has cheated on a spouse.

If it's a one-time transgression -- perhaps a fling on a business trip -- it might be worth keeping that a secret from your partner, said Karen Sherman, a psychologist in Long Island, New York.

Some therapists might say honesty is important if there is to be healing in the relationship, Sherman said. But her own view is that it depends on the individual case. "Sometimes there really is more damage caused by telling it," she said.

However, if you're involved in an ongoing affair and living a duplicitous life, you should end one relationship or the other, McDonald said. "I think it's important to really take the time to introspectively look at all aspects of your situation."

The purpose of secrets

Shame, fear of embarrassment or fear of not being accepted often are the motivation behind keeping something secret.

But the anxiety that comes with some secrets isn't entirely bad, von Reiche said. Like nausea, "anxiety is your mind's way of telling you that something you are carrying needs to be purged," she said.

In other words, you may feel better if you get it out in a safe place, such as by confiding in a trusted friend, family member, community leader or mental health professional.

Therapists will keep your secrets except under certain conditions, such as if you are endangering yourself or others -- that's mandated by federal and state laws. If you are having suicidal thoughts, this is not a secret you should be alone with. Call the National Suicide Prevention Lifeline.

But the main message in many of these scenarios is that you should weigh the consequences -- both to you and someone else. Think about whom you tell, how that person will react and whether you will both be better off.

"If the world were ready to be accepting of everyone, it would be a better place," McDonald said. "In an ideal society, we would have no secrets. Do I think that's likely in your lifetime or my lifetime? No."

Are you holding on to a secret? Tell us in the comments.