Saying things and not following through portrays you as someone that speaks words with no substance. Being intentional about what you say, and then following up with being intentional about your actions makes you a more confident person and makes you feel like you are really getting stuff done.
doing what you said you were gonna do...goated and rare behavior tbh... 9/10 times you're gonna be glad you made yourself go to the thing you said you would go to even though you don't really feel like it now that it's 30 minutes before you're supposed to leave...just go. being reliable >>>>>
And then completing it. Applies to "I am a person who will cook themselves a nutritious meal" etc. Not 100% effective, but makes me feel deeply determined when the scheme works.