Love is...
I came to a realization while talking with a friend this weekend:
Love is an involuntary action, much like breathing.
You need both to live, but you don't decide when it will happen. You can try to stop being open to love - to letting it into your heart again, especially when you're in pain from a lost or unrequited love - but just as with breathing, you'll suffocate and die without it. Sometimes the love is shallow, small gasps that are just enough to keep us going. But sometimes you can open wide and pull its fresh, beautiful, cleansing essence in completely.
When you run out of breath, your body feels weak and your head sickly spins. So it is when love escapes our reach. In both cases you turn blue until the next breath comes along...
You know... come to think of it, the heart itself is an involuntary organ.