From the conclusion -
One of the most deflating concepts facing positive psychology is the hedonic treadmill (Brickman, Coates, & Janoff-Bulman, 1978): Even though positive and negative events (e.g., winning the lottery, becoming paraplegic) temporarily alter levels of happiness, people quickly adapt to them and return to a fixed emotional set-point. The hedonic treadmill, as classically stated, implies that all efforts to improve happiness are doomed to failure. Yet more nuanced research (Diener et al., 2006) indicates that adaptation is not necessarily inevitable and may be strongest for negative affect and weaker for positive affect and life satisfaction. The evidence reported here reveals that one way to outpace the hedonic treadmill is to begin a practice of LKM. Participants who invested an hour or so each week practicing this form of meditation enhanced a wide range of positive emotions in a wide range of situations, especially when interacting with others. We find these data especially promising. LKM appears to be one positive emotion induction that keeps on giving, long after the identifiable “event” of meditation practice.
Positive emotions feel good, and feelings like love, joy, and contentment can be valuable in and of themselves. Yet the broaden-and-build theory posits that natural selection sculpted our ancestors’ positive emotions to be useful in more far-reaching ways as well. These desirable states built resources that gave our ancestors’ an edge in circumstances that impinged on their survival. To our knowledge, this is the first experiment to provide clear support for the build hypothesis. By random assignment, one group of individuals began a mind-training practice that increased their positive emotions and, in turn, their personal resources and well-being. Just as the broaden-and-build theory predicts, then, when people open their hearts to positive emotions, they seed their own growth in ways that transform them for the better.
If your mindfulness of breathing is getting a little too dry, perhaps some metta as kusala sankappa (wholesome intention) would lubricate it.
Also from Fredrickson's team -
for a plausible mind-&-body connection.