An interesting article in today's guardian lists five things which 'successful' PhD students refuse to do. I think the article is a bit too simplistic. I know plenty of successful PhD students that have stressed about getting published or felt out of control at times.
As a PhD student I can relate to many of the things to discussed in the article. I have discussed with several other PhD students how early on the PhD you can feel that you don't deserve to be where you are. I remember saying "how did I get into Oxford? I must have slipped through the net!!" I think it is essential to go through these various feelings. Being a PhD student can be an emotional roller-coaster at times but I think that's what turns you into a better researcher in the long run.
When my first year as a PhD student became a daily grind of going to several classes a day and learning endless new experiments and procedures in the lab, I looked around for inspiration from older and more successful students. What were they doing differently? I eventually realised that the high-achieving postgrads all had one thing in common: refusal.