For me, creativity is the stuff you do at the edges. But the edges are different for everyone, and the edges change over time. If you visualize the territory you work in as an old Boston Bruins sweatshirt, realize that over time, it stretches out, it gets looser, the edges move away. Stuff that would have been creative last year isn't creative at all today, because it's not near the edges any more.
It's true, creativity is moving all the time. That's why if you write an idea down and forget about for a few years, you'll likely find someone has already done it by the time you get around to it. Seth uses this to persuade you to spend more time near the edge, which I agree with.
However, since creativity is a moving target, doesn't that mean we should be moving quickly on our ideas? Each creative impulse we have is correct for a moment, but that moment will pass. Don't spend time on the edge and then not take action. That's the definition of creative frustration.
Act quickly and often, that's the way to make progress. If you don't, you're just setting yourself up for regret.
We've all had to sit next to that guy on the bus that claims he invented Post-It notes in his basement in 1967, but never got around to doing anything about it and now all he has left to do is ride the bus and tell the same story over and over again about what an unrecognized genius he is.
Don't be that guy. And don't sit next to that guy if you can help it, his breath smells like tuna fish and socks.