When to use it
Use it when someone praises your work. A simple thank-you plus one line about what you're proud of is gracious and confident. Brushing it off can make the other person feel their judgment was wrong, and makes them less likely to praise you again.
Example
Director: “That presentation was excellent.”
You: “Thank you. I'm proud of how it turned out.”
In an email or Slack message
In Slack: “Thank you! I'm proud of how it turned out, and Jamie's data work made it possible.” Sharing credit is fine, as long as you accept your part too.