"The Unsatisfactory Nature of All Existence"

I'm almost finished reading, "Mindfulness in Plain English," a primer for mindfulness meditation written by Venerable H. Gunaratana Mahathera.  Towards the end of the book he writes,

"Through this intensive study of the negative aspects of your existence, you become deeply acquainted with dukkha, the unsatisfactory nature of all existence.  You begin to perceive dukkha at all levels of our human life, from the obvious down to the most subtle."

Have I ever!  I've started to notice how I gravitate towards pleasant experiences and how I tend to get caught up in negative emotions and have difficulty just sitting with them and exploring them with mindful curiosity.  I've become increasingly alert and aware during enjoyable activities and when I find my mind slipping away from the present moment I catch myself and remind myself to be present.  The thing is I'm catching myself doing this A LOT -- I'm definitely a thinker and my mind seems to always try to slip away from the present moment.  I get frustrated with repeatedly having to remind myself to fully experience whatever I'm doing so that I can fully ENJOY it.  I"m wondering if this is causing me to enjoy things less than I did before.

The thing is, though, I'm not sure how much I was really enjoying things before.  Maybe I'm really experiencing the fullness of life for the first time and am just frustrated with the fact that my mind keeps pulling me away from it.

I am, however, fairly confident that this is just a passing phase on my journey...