A sense of direction does not mean "forswearing experimentation". Without a direction you aren't going to get much accomplished. I spent years thrashing because I was (and am) interested in almost everything.

Besides the Paul Graham essay, you might want to read the Study Hacks series on deep procrastination, especially this one.

procrastination, in my experience, is not a character flaw, but instead evidence that you don’t have a believable plan for succeeding at what you’re trying to do.

Enjoyment isn't enough nor totally necessary (though it can make the work involved feel easier). The most important thing is to have a specific goal and a believable (by you) plan to achieve it.