What makes a phd life tick?

This is something that I have been thinking about for quite sometime. Phd life is life lived in 4-5 years. Its been just 1 year so for me in my program and I have had numerous ups and downs. What I have understood is that to come out successfully out of the Phd program there are a few things in non-academic life that need to be taken care off.
Phd life = Academic life (research + a few courses) + Social life (friends) + Some other passion (books/physical activity/music/...). These three components need to be well-balanced for a Phd life to tick. Lets look at these components in detail:
i) If you lose interest in your area of research, its very difficult to continue through a Phd. You may lose interest because you might have had a different concept about what a Phd might be before you began the program. You may lose interest because its a relative thing... you are more interested in working in some other area. You might lose interest because you are tired of the rigors of a Phd program.
ii) You got to have a few close friends you can count on when you need them. It has been my experience that I am immersed in research for one or two weeks, and when I come out of the research world, I am craving for social interaction.
iii) Many times doing research could be frustrating , so you would be looking for some change in your life. This is where an already existing habit or hobby such as book reading or physical activity such as running might prove very useful.

Balance is the key word. All the three components need to be balanced for a smooth ride through the Phd life. Imbalance could lead to minor frustrations or even major episodes (depression, etc).