Next time someone thanks you and you’re tempted to say “It was nothing” or “It’s the least I could do”, consider instead saying something like “You’re welcome! Doing this brings me joy”.
If someone is thanking you, then presumably you did something generous. Being generous is by definition “showing a readiness to give more of something than is strictly necessary or expected”.
Maybe what you did to merit being thanked really was just what was strictly necessary or expected, but maybe not. It’s ok to own your generosity.