Andrew Oswald gives us, "Things I would have found it useful to have been told when I was a young researcher".
Well worth reading the whole thing, but here is a good bit:
"The main difference between world-class researchers and sound researchers is not intellect; it is energy, single-mindedness, more energy, and the ability to withstand what will sometimes feel like never-ending disappointment, tiredness and psychological pain. Tenacity is almost everything."
I have found this, along with much of the rest of Andrew's piece, all too true.