When you're doing something hard, the effort curve looks something like a bell curve. At first, as you're dabbling in it, you don't put in much effort. Then it progressively gets harder and harder until you finally reach that peak. That's when you "make it" and things start to get a little easier. But we don't always make it to that peak. Sometimes, often, we give up.
Polyphasic sleep was brutally difficult. I tried three times to get on the schedule. The first two times I gave up on day five because it was just too hard and there was no end in sight. Then Steve Pavlina got on the schedule. He announced that on day six it gets easy. I tried again, and sure enough on day six it got easy. It's not that it took no effort after day six, but when the effort required is less and less each day, it's really easy to persevere When it's harder every day, well, that's a different story.
Pickup was like tights, too. At first it was murderously difficult to get a girl to even talk to me. It was painful and showed no signs of getting easier. I stuck through it somehow, and I still remember the day I realized it had gotten easier. I was talking to a friend and told him that pretty much every girl I talked to those days would be attracted to me in some capacity. It struck me that I could have never said that before, and that I had in fact reached that peak of effort and passed it.
It's like climbing a really densely fogged mountain. You have a rough idea of how far you've come, you can see how difficult the patch you're working on is, but you can only have the vaguest idea of where the top is. Maybe it's a day away, maybe it's a year away.