Kelly Clarkson is glowing -- and has good reason to be.

She recently got engaged to music manager beau Brandon Blackstock, and their love has been a main reason for the singer's happiness.

"I didn't know life could be this happy," she tells this week's issue of PEOPLE magazine, which features the bride-to-be on its cover.

Kelly is excitedly planning an "earthy outdoor all wedding," complete with yellow roses, the mag reports. The fall nuptials will also include a special performance by their good friend, Blake Shelton, who happens to be managed by Blackstock.

"Blake actually is going to play at our reception, so we're pretty excited," she confirms to radio station K-Frog.