If you're dealing with a friend who's placing unreasonable demands on your time, wallet or sanity, there are a few ways to handle it, writes NYU psychiatry professor Irene Levine on her website The Friendship Blog. She suggests setting boundaries, for both yourself and your friend. Don't give more than you can, or more than you feel comfortable with. If your friend constantly demands your company or attention, for instance, Levine recommends letting her know you have other obligations, as well as limiting your time together to once a week. It's OK to say "no" to your friend -- in fact, she writes, "good friendships should allow for this possibility."

When it comes to a needy co-worker, a direct, assertive stance is best, advises New York Times writer Rob Walker in his column "The Workologist." If you have a co-worker who comes to you whenever he needs help, Walker suggests deflecting his questions with something like, "I have a lot of work to do right now -- you can look that up." If that doesn't work, Walker advises sitting your colleague down and politely, but honestly, telling him you have your own job to do, and you can't be doing his too. Should the situation get out of hand, Walker recommends taking it to your manager.

A needy significant other can drive a wedge between you and the person with whom you once wanted to spend all your time. Before you decide that her clinginess is too difficult for you, writes psychiatrist and Psychology Today contributor Dr. Mark Banschick, there are solutions you can try. He suggests learning to give each other space, creating a foundation of mutual respect and even therapy, if your partner is willing. He also recommends analyzing your relationship, specifically looking for any issues that might be contributing to her needy behavior.

Although it can be hard to say "no" to family, overextending yourself to avoid feeling guilty or disloyal to a relative is a form of unhealthy behavior. You need to set boundaries, says psychotherapist Ross Rosenberg in an interview with psychcentral.com, and to do so in a way that doesn't shame or judge your relative. When your mom pushes you to call and text her several times a day, don't push back with a, "You're suffocating me, back off." Instead, Rosenberg advises acknowledging that your mom is acting out of love, and suggests setting aside specific time during the week to talk.