A feeling that is larger-than-life. You realize that life is more than a collection of mundane, daily activities; life is more than "this is satisfactory and pretty okay, and as good as it gets." Yes, sometimes life is like this. A "pleasant grind," at best. But why settle? Life can also be more.
That's what magic feels like. You don't really know how it feels, until you feel it. When you feel it, you just know what it is. You just know.
Truthfully, feeling magic is scary. You don't know where it came from, so you don't know how long it will last. It can run out at the next moment. You live moment-to-moment.
Some people look for magic in the wrong places. I understand. I've done it. They're in love with the idea of love. They want to feel things, without substance and reality to back it up. Or they always live on the edge, to feel that constant rush. Or both.
Those things aren't really magic though. They're weak imitations of it.
Magic is mysterious, but that doesn't mean it's free. It actually takes some work to find it. What kind of work? Be honest with yourself. You'll know.