Several years back I was privileged to attend a poetry workshop at the university where I taught. Rebecca Balcárcel presented.

Instead of linking to the original post, I am just going to copy the exercise here.

Exercise
Describe an object in your closet (garage, storage unit, attic, basement).
Use personification (make this object behave as a human; have it take action or talk to you).
End with advice that the object gives you.

I realize that this is for poetry, but I think it might be fun for picture book writers. Whether it ends up being relevant or not, writing it will build your creativity muscles.