I was just watching this video over on Paul Coelho's blog and I thought I'd add a comment, drawing a direct relation between peace and its sustainability, alongside inner balance and its sustainability.
It's like I say, to live a good lifestyle you need balance in at least two major aspects, work and rest. However, how you define and understand the words work and rest are individual to you as a person and not as simple as they might first appear.
Furthermore if internal peace is the attempt to attain inner balance over these two elements (and others) then one can quickly find that achieving true balance is an every day thing that requires rest in order to make it work and focus in order to make it happen.
So what I am trying to say is, balance is an ongoing every day work in progress and at this moment in time (I'm 23) I believe it has to stay that way until an equilibrium (Not a peace) can be achieved for the individual and not everyone.
So in life peace is an ongoing struggle, but at some point an equilibrium can be achieved, which is not the exemplar of peace, but is the exemplar of "what works".
That seemed like the best analogy I could draw, it will be far from perfect as the years roll on I'm sure. But that's the whole point, just as Paul states, the whole thing is ONGOING. Just like Meditation in Buddhism is not the whole journey, but part of the journey toward enlightenment (for Buddhists) or part of the journey through life (for non-Buddhists). I should point out I meditated for nearly a year with dramatic effects psychologically and physiologically, it was an amazing test, but it was part of an ongoing process, not the only path toward attaining a better understanding of myself.
I'm sure more rejections will follow soon! I've just sent off a query letter today.