There is much of this advice that I did not realize before or follow, which could be why I have struggled so much with my PhD. I don't think grad school is "easy" for anyone, but some people seem to enjoy their research so much that they spend a lot of time on it and are quite successful, while people that do not have as much motivation, experience serious setbacks, or whose hearts aren't in it find it very difficult and stressful. It is definitely a large decision to decide to get your master's or PhD, and I don't think people should choose this path because they don't know what else to do, or are waiting for the economy to improve, etc. Also, grad students should know that their expected career paths may change from before they enter grad school after they experience a life surrounded by academia.
However, a very good piece of advice I think I especially need to keep in mind is: "Contain the perfectionist, remembering that sometimes done is better than perfect, and to the extent that you can, spend your time doing interesting science and cultivating your ability to do interesting science."