If you are in your element, you feel happy and relaxed because you are doing something that you like doing and are good at.
"You should have seen her when they asked her to sing; she was in her element."
Said when someone has expressed a desire or opinion, meaning "That viewpoint is not unique to you". It can suggest that the speaker should stop complaining since many others are in the same position.
Example: "If this train doesn't come, I'll be late for work!" "Join the club!"