Momentum is what keeps us going—a good thing if you’re heading in the right direction (not so great if you’re heading off a cliff). “A body in motion stays in motion,” Newton taught us—unless it encounters friction, forces pulling it off course, or sudden appearance of a brick wall. And there’s the, er, rub. Resistance, distractions and obstacles are the stuff of life. Which makes it all the more impressive when people not only create their own momentum, but keep things rolling, growing, and gathering momentum along the way. For our April 19th Categorically Not! we’ll hear from experts who’ve used momentum to skateboard into public diplomacy, make LA the envy of the lit world, and become rock stars.