I created this in FlipaClip as a sort of digital card for my wife's 40th birthday.
It started as an idea with just the phrases "You're gorgeous, smart, and funny. You're a star, an angel, and maybe a little devilish." I then drew the frames for each of those six descriptors, before starting work on the animations to transition between them.
I think the star to halo to devil sequence works especially well.