being full of or promoting cheer; having or showing good spirits
"her cheerful nature"
"a cheerful greeting"
"a cheerful room"
"as cheerful as anyone confined to a hospital bed could be"
pleasantly (even unrealistically) optimistic
"Despite the looming storm clouds, she remained cheerfully convinced that the sun would come out tomorrow no matter what happened."
Noticeably happy and optimistic.
"Despite the rainy weather, she remained noticeably happy and optimistic as she greeted everyone at the door with a bright smile."