Historical clue formulations

• "Definitely, leave it to me!" — 2023-10-15
• Confidence-building mantra — 2022-09-25
• Confident shout from an optimist — 2022-01-18
• Optimistic assertion — 2020-09-20
• "Sign me up!" — 2017-06-16
• Sammy Davis Jr. autobiography — 2009-11-01
• Positive thinker's proclamation — 2003-04-10
• Sammy Davis Jr. autobiography — 1999-07-22
• Non-defeatist declaration — 1998-09-25