Since we're on the subject of interesting characters, let's think for a moment how those characters pop into your story. Allow your mind to form sentences and questions that you don't know the end of even as you begin. For example:
When the doorbell rang and I opened the door, I did not expect to see ________.
When she said she'd be "hanging around the gym," I didn't think she meant literally.
Homework: Again, practice letting your mind wander and float. Allow sentences to form in your head and follow them like a curious puppy to see where they end. Listen for the voice of who speaks those sentences. Is it yours? Or does it belong to a character waiting to be discovered?