Accept joy. Think about a little girl being tickled by her beloved father, both of them delighted and silly and present with each other. In the same way, Love delights in you with exuberant joy.
Sometimes we reject this kind of joy because we fear happiness isn't serious: if we experience lighthearted delight, we won't finish our work, we won't recognize the depth of the world's suffering or do anything to fix it. We fear we don't deserve joy. We haven't earned it. We fear that if we experience joy, it will just be taken away from us and we'll feel even more flat and sad in its absence. Those beliefs reject a gift being offered us.
Accept the gift. Savor joy wherever you see it, even the faintest glimmer. In a glimpse of the full moon, in a spontaneous and genuine hug, in some time with someone you love, in a delicious homemade meal, in music, in a laugh with a stranger in a store.
Second:
Today, also know that you don't need to manufacture the energy to do what you need to do, you don't need to push with will or hold your muscles tense or worry your way into accomplishment. Instead, feel Love's energy, revitalizing you, moving you.