"Morning" is a short, quiet celebration of the start of the day. The speaker admits that days can be groggy or foggy, and that most of them feel pretty much alike. Mornings are the one thing that changes, even if they don't really affect how the rest of the day goes. Still, the speaker calls them "the best part of living."
The reasons given are simple: birdsong, a good cup of coffee, and the plain fact of waking up and realizing you're "still here." That last idea gives the poem its weight. Beneath the cozy details is gratitude for being alive for one more day.
The mood is warm, calm, and easygoing. The short lines and repeated "Mornings are waking up to" give it the feel of a gentle list of blessings. The final line, "Mornings are great," is blunt and cheerful, like a contented sigh rather than a grand statement.