
Regardless, another factor in my success was having a somewhat crazy officemate who would work 30 hours straight and then sleep 13 hours, 7 days per week (we are still good friends and he is now a well known deep learning theory professor). I couldn't do that, but the zeal with which he pushed himself motivated me a lot (although he also gave me imposter syndrome since we took some proof heavy courses where he would be done in a couple hours what would take me days to do the same assignments).
I definitely don't recommend having kids during a PhD, as I've seen many students and peers struggle tremendously. A partner is great, especially if they are equally busy (mine was in medical school across the country), because one isn't going to really get a lot of nights and weekends if you are really pushing yourself. My advisor never pushed me, but I pushed myself very hard.
Still, if one just wants a PhD, what one needs is a good advisor who can steer one towards problems that are tractable given the student's abilities, stable funding (most programs worth doing are reasonably stable), and not trying to think one must do the most amazing work of their lives during their PhDs. It is a lot of work, but a career in research and the privilege of cultivating the next generation is really what makes me feel self-actualized.
I try to find low-hanging fruit research projects for my PhD students in their first few years to build up their confidence and then have them pursue harder problems, where if the harder ones don't work out they still hopefully have enough stuff to form a dissertation. I often find myself needing to be more of a cheerleader for my students nowadays, though, since my field exploded and reviewers seem much less competent. Rejected papers for good work hurts mental health.
[1] http://www.goodreads.com/book/show/460669.Getting_What_You_C...
Another really helpful read was "Getting What You Came For" by Robert Peters. He walks through the entire Ph.D. process and describes a pipeline that can knock a 7 year program to 4 or 5 and a 5 year program to 3 or 4. That time saved would be incredibly valuable.
I'm always on the hunt for good material like this. What other Ph.D./grad school/research guides have people found helpful?