Confident or Overconfident?

Been a long time, too long perhaps, but I survived my first semester as a Ph.D. student and am entering into my second. Lately, the idea of "success" as a student and in the academic career that will (hopefully) follow has been weighing heavily on my mind. It just so happens to be aligned nicely (or perhaps frightfully) with an article in The Chronicle of Higher Education on job prospects for Ph.D.s (The Odds Are Never In Your Favor). 

For the most part, since I've decided to go down the path of pursuing a Ph.D. I've been confident that I would succeed. This may be in part due to the professors in my master's program encouraging me down this path, suggesting that I would be brilliant and fully capable of success, but it's also knowing that I've made it this far already. Don't get me wrong, there are plenty aspects of this road I'm travelling that frighten me. Comprehensive exams, getting published, dissertation, finding funding for travel to conferences, entering the job market and totally relocating yet again. Despite all of that, I still think of it as taking just one step at a time and that it is all conquerable. However, is that outlook detrimental?

I'm not naive enough to think that I won't question it or that I won't want to give up, but maybe this confidence I have can do more harm than good. Maybe when it comes time for me to face this giant hurdles I will not face them with the caution that I should, and I will find myself pushed to the brink wondering what will happen to me if I break. Along the same token, I think too much caution, too much fear, of what lies ahead is dangerous. If I constantly fear the unknown and what has yet to come, how can I ever make the bold choices that I may need to make?

Maybe it's not an issue of confidence after all and it's just a matter of having a positive outlook on life. Thinking that I'm here for a purpose, even if I don't know what that purpose is, and the only possible way forward is for me to succeed.