Mindful Joyfulness/Joyful Mindfulness

So this is a bit of a slippery fish for me right now. An important part of my practice right now is increasing my awareness of every moment, which I am making some headway on. However, lately I've been struggling to be joyful when I am practicing mindfulness. Thich Nhat Hanh frequently speaks of recognizing our difficulties and smiling at them, but sometimes this is oh-so-hard for me. Doing this - greeting my experiences and feelings with joyful, mindful acceptance - can sometimes require a tremendous act of faith on my part. In An Introduction to the Four Foundations of Mindfulness, Lama Lhundrup says:

Then, through contemplating the nature of samsara, we should relinquish all desire, all wanting, all clinging to the cycle of existence and dissolve all sadness and evil-mindedness. With "sadness" the Buddha meant the sadness which arises in the beginning when we take the resolution to leave samsara behind, an uneasiness due to leaving our beloved attachments. There should be no such sadness in our mind when we are letting go of the causes of suffering (!), but rather the great joy of a firm resolve to go towards liberation and to become able to make it accessible to all others as well. In order to practice mindfulness it is very helpful to have the support of a joyful aspiration.

Mindfulness is the practice of those who are happy to get out of samsara. Our basic attitude of mind should be free of clinging to this world. Having this as our basis we can develop the four foundations of mindfulness. For this we have to practice with diligence and with a clear, precise knowing of what we are doing, with clearly understood instructions on our meditation. Mindfulness means not to be forgetful, not forgetting the object of one's intention. Mindfulness needs to be accompanied by equanimity, a stable mind, not impressed by whatever might appear in mind, and it should be continuous, without interruption; not sometimes mindful and sometimes not. A continuous mindfulness is actually based on a deep letting go, just as Gendun Rinpoche always instructed us. Mindfulness establishes itself naturally when we have no interest for the world and let go of our worldly preoccupation.

It is this joyful aspiration that I am trying for right now.