Setting ambitious targets and remaining zen - is it possible?

As a professional project manager, I pride myself on being well organised. I set and reach my goals in all aspects of my life, all while managing to stay on the right track. Up to that point, all is going fine. Overall, I'm happy with the results in both my personal and professional life. However, I find it difficult sometimes to be satisfied with what I have managed to complete during the day.
That's despite the plethora of methods and good advice available to me: being efficient and remaining effective, following the GTD method1, putting first things first2, managing tasks, taking time out for yourself, family and friends, practicing sport, eating well, remaining zen. How to not get snowed under with such a huge to-do list? How to not overload my days? How to be satisfied? Not always very obvious, is it?
I would like to share with you a 'light bulb moment' that came to me following my various summer readings. I realised that you can have two methods for evaluating your performances, one for "today" and the other for "the future".
The future will become clearer and evolve over time depending on our objectives and plans. This method will involve comparing our results and goals at specific moments in life and adjusting them accordingly. Our progress towards reaching our future goals will be assessed at regular pre-defined intervals (weekly, monthly, annually, etc.). Then, as soon as one goal is achieved, you set another. There is, as a result, a risk of losing sight of where you are going and of wearing yourself out.
The method for assessing "today" is less structured and helps us avoid this pitfall. It simply involves assessing our choices throughout the day in relation to our principles and values. This is instead of assessing yourself on whether you have ticked off all the things on your to-do list (virtually impossible for most people). The idea is to link our goals with our values and life principles.
Two examples:
For any project, the fundamental principle is to achieve the goals of the project. As a project manager, if the project is big enough, you are in danger of being overwhelmed with the amount of tasks needing to be done. How to pick? Prioritise the tasks which will have the largest impact on reaching the aims of the project. Will spending time with a team member really help you more to do this than writing a report? Depending on the context, it may be that either one or the other is the right option, even if this task wasn't originally on your to-do list.
You woke up early for a meeting and feel tired. You must hand in an article by the end of the day. Two principles are at stake here: