Vairagyam. Pronounced vi-rahg-yum. Sanskrit for detachment, letting go. A very important principle of yoga, and very difficult to achieve.
It doesn't mean being all serene and mellow, just letting the world drift by. And it doesn't mean not caring. What it does include is observing where you are enmeshed, anxious, judgemental, even, and making the choice not to become stressed or angry or overwhelmed by things that you cannot control.
Example, and a mundane one to start. This comes from my teacher. You love chocolate ice cream. You love it more than life itself. You go to your favorite ice cream store for the very best chocolate ice cream in the universe. And go figure, they're out of it. Here's the choice: you can either rage and scream, or internalize the disappointment so that you make the Eeyore move of "poor me," or any of a number of other worked-up responses to the lack of chocolate ice cream. Or, you can acknowledge your disappointment, and without going into a tailspin, choose another flavor, or go home and come back another day for the chocolate. Vairagyam: you can still be sad, but not so agitated that all that you can focus on is the emotional upheaval brought on by the no-chocolate reality.
Another example, this one a bit more complicated. It's your birthday, and once again, your brother or sister or best friend has forgotten it. Hmmm. Here's vairagyam: you observe to yourself that she is forgetful, and that although you never forget her birthday, that she invariably neglects yours. Vairagyam: you could tell her that you are disappointed that she never remembers, that it matters to you, and could you plan now for your birthday next year so that she doesn't forget?
Letting go of the outcome is tough. And taking our responses to life not going our way brings up all the old stuff, the samskara, or patterns, that we have come to adopt like long-lost children. But here's the pay off: being able to move on, being able to take all that energy that went into anger and gossip and recrimination and even, and too often, violence against one another, and turn it toward something more purposeful.
Here's a homework assignment, if you're interested: notice, as you go through today, the mood of those around you. It is September 11th. Are we still stuck in the events of 2001, or have we found a way to take that terrible moment and find something to learn or grow from it? Not to forget, or to erase, but to be observant rather than angry, able to salvage something worthwhile and not endlessly swirl in vengeance or hate.