One of the ways you cause yourself suffering is by making up a story. What do I mean by this?
Let's say you have a friend whom you've invited to a party, and she says she can't make it. Maybe she gives an excuse, maybe not.
Whatever she says or doesn't say, you can cause needless suffering by telling yourself a story. "She doesn't want to come because the last time I saw her I made a political comment she didn't like, and now she likes me less. Or maybe it's because she's upset that I didn't call her back that one weekend when she invited me to see a movie. Or, maybe she just finds me boring and doesn't want to spend a Saturday night hanging out with me."
Whatever. You could go on and on. And because people do behave according to some internal motive, it's possible that any of the above reasons are the ones she doesn't attend the party with you. But without asking her point blank, it's impossible to know for certain the reason why. All of the stories you've told yourself are pure conjecture, and none of them might be true. It could be that her grandma died. Or she has swine flu. Or she is having one of those weekends where she wants to sit on the couch and read a huge book she's been meaning to get to.
The point is, you cannot know. But in the meantime, what are you doing with the stories you're telling yourself? Causing needless suffering for yourself. Feeling hurt and depressed. Wondering what's wrong with you.
None of these things are useful. If you truly fear that something is wrong between you, don't make up stories. Uncover the truth. If you've been a bad friend, she'll tell you. (And if she can't talk to you, or she changes the subject, then you've learned something about the nature of your relationship, which you can then utilize later to make a decision about how to proceed.)
This story-telling can cause problems anywhere in life. Before I began practicing yoga and tai chi, I had developed a pretty bad case of runner's knee, especially after I completed a rigorous training schedule for a marathon. Even after the marathon ended, the pain went on and on--not just for months, for years. I ran through it, it would flare up, I'd rest, and it would feel better. Then I'd run again, and voila, back to the pain. The pain was just pain. But the suffering came in when I would tell myself that I'd never run again or that I had permanently damaged my body or that I'd get fat like that health teacher I had in high school who told us she'd injured her hamstring and had never been able to be physically active again.
Every time the pain would flare up, I'd tell myself these stories. I'd grow sad and frustrated and angry.
Though I didn't know it at the time, yoga and tai chi would heal my knees completely and I'd be able to run again. None of the stories I'd told myself turned out to be true. I believed those stories at the time, though, and suffered more than I would have just by feeling the pain.
So, what stories are you telling yourself? Are they true? If you think they are, do you know they are? Really, do you?
In yoga, I've learned that feeling discomfort can be observed without any narrative. I can just feel, just be, and the burn in my legs just is. I can become detached and observant, like a Buddhist monk. (Well, maybe I get close, anyway.)
The next time you hear yourself making up stories about why something is, or how something will be in the future, stop yourself. Ask yourself if you have any basis for the story. If not, take a deep breath and clear your mind. Just be. Just feel. No thoughts. No judgment. No stories.