I was just out for a run. I have some great ideas when I'm running; something about the oxygen deprivation, perhaps. I have trouble remembering them when I get home. Perhaps "great" is a little extravagant, but good anyway. But plenty of ideas--they just seem to well up.
Maybe it's that the blood is flowing.
Exercise is a good metaphor for the writing process. I've always had a good relationship with exercise--I like it, it's easy for me to work at it. I've had a less positive relationship with writing and academics; it's hard for me to work at it. But with writing, as with exercise, we can develop a good relationship with it by re-approaching it.
With exercise, if you go for your first workout and you push yourself to your uttermost limits, you can end up sore for days, and you probably don't enjoy the workout. What kind of incentive is that? And you're not really ready for it anyway--your muscles need to adapt.
With writing, you may not get sore, but if you expect to suddenly develop a good relationship with writing by insisting that you'll write for some very long period each day--a period many times what you ever worked before--you're setting yourself up for some problems. Some people, I'm sure, could pull this off--suddenly become a writer--but others would work hard, get little done, and get frustrated and perhaps despairing for the project. I've seen it with clients: people swear to me that they're going to start writing for hours every day, and then the next week they're angry for not fulfilling their goal.
I had a client once who had been focusing on a quote about writing that said something like "writing is staring at a blank piece of paper until your forehead starts to bleed." Not surprisingly, she didn't feel particularly good about writing. IF you enter into the project of writing expecting it to be painful, you carry an emotional burden that hinders your progress.
Yes, writing does take effort--like exercise. And, like exercise, writing can be pleasurable; the effort, indeed, adds somewhat to the pleasure. But this only happens if we approach the project from the perspective that we have to recognize that the process of writing is one that we can better grow into than be thrown into.