like a duck to water
Very quickly and naturally, as if it were innate. The phrase also often implies a sense of enjoyment. Sarah took to her bike like a duck to water. She was born to ride. I wasn't sure if he'd like playing the piano, but he's taken to it like a duck to water.
(take to something) like a ˌduck to ˈwater
(be able to do something) naturally and without any difficulty: ‘Do the children like living in the country?’ ‘They’ve taken to it like ducks to water. They’ve never been happier!’