Not to be confused with “effervescent"—that’s too bubbly. Today, you’re just really, energetic and—without being over the top—full of good vibes.
People look at you and say, "you look pretty happy”. And you say “thanks, I do feel good” and you both nod go about your day. There’s a spring in your step, you might whistle, or even occasionally click your heels, which is actually quite hard to do.
You feel so good that you choose to project your feeling onto the reader, because admitting you feel this good carries the understanding that you will soon not feel this good.
And that is a prospect you fear.