Why to do a Phd

I had already formulated my opinion about why to do a Phd, after reading the book I mention is this post. I must say that after that book I was frightened about the implications for personal life when you are doing a Phd. The part when the authors mention that it may harm your relationship with your family, and that sometimes a Phd ends in family rupture was not very promising.
Recently, we had Prof. Tim Kovacs from Bristol University visiting us and his lecture about Aims, Objectives and Guidelines for Phd Students was inspiring. I was also more comfortable with some issues he mentioned, and, at this moment, feel confident enough to believe I can do it. I can do the Phd.
What I thought might be a non valid reason for doing a Phd ends up being a good one. Thus, I love to learn and I am also curious, though I do not see myself as creative, and I am not so much optimistic that I can contribute with something valuable to the world. About challenges, I think it is desirable that we have some in our life, but I am not very comfortable in being challenged all the time. Sometimes I feel I need inner peace, and when I have a challenge I cannot find that peace.
What I noticed was that the first reason I had for doing a Phd has changed, as I feel I have somehow matured this question. When I first met the Coordinator of the Doctoral Program with my previous supervisor, I was not sure that I really wanted to endure in this task. This aspect was clear in me, though I did not know, and the Coordinator caught me immediately. He asked me, "So, you want to do a Phd?", and my answer was, "I think so". He replied, "You think so, or you want to?", and it was my supervisor who rescued me confirming that, "She does want".
She did not know by then, but I was really insecure in my purpose. Or maybe she did know... by that time I was trying to find what I would like to work on. Teaching, banking, mothering?... I did not know what I wanted to do in my life.
When I submitted my proposal to get funding from FCT, I was more enthusiastic about my reasons for doing a Phd. I had been at home with my son almost 9 months, and finally started to have my own life back. On the other hand, we had recently moved from Portugal to Boston, and this had a great impact in our family life, with my husband being present more often. Still, I was not completely engaged with my objectives for the Phd. I had a few entrepreneur ideas that I wanted to try, so if I did not get the funding I would be very happy with my entrepreneurial projects.
It was only when I really started working in the Phd, after December 2009, that it struck me: "Hmmm, I really like learning. I like to understand things. I feel great when I learn something new." Then, maybe it is not such a bad idea to do this thing of Phd...
Professor Tim Kovacs highlighted some aspects that I had not thought about. Working in a Phd brings you freedom. You have the privilege of having time and freedom to follow your interests, and a Phd is about a journey, not about a destination. It is a common error to think that the goal is only the destination. It makes the journey a big frustration, a big sacrifice, and we will not enjoy this at the end. Many researchers do not recall their Phd years as a positive experience. I am determined to make this not happen. I had enough of work I did not like in my first working experience, which lasted for 5 years!
Other great idea from Prof. Kovacs is a form to help students thinking about what they need to improve in their researcher skills. This form lists the activities and the objectives they contribute to in order to provide evidence of lifelong learning, seeking feedback, and developing transferable skills. I already have some ideas of activities to fill in this form, but first need to clarify my research question.