Students thinking about applying to a PhD course sometimes wonder whether they would be able to complete the PhD course, whether they are smart enough or tough enough to finish and get the final degree. In reality, the answer is that it is not about how smart or talented you are, but rather whether you are able to push through and perservere. You need to commit to this course of action and then just keep going until the end. Having gone through the process myself, but having also seen students struggling with it from the other side, I can see a number of patterns here. The most important one is that the students who do not finish are not the least smart ones.