People respect CONFIDENCE!
But not TOO much confidence.
If you think you can lift a boulder, and at most you can lift a sandwich, dial it back a bit.
No, that's too far.
Look, just be exactly the right amount of confident that nobody can legitimately call you out on it.
Or, if they can, have a perfectly good excuse for not proving you can do what you just claimed you could do. Accepted excuses include "I don't have to prove anything to YOU", "I'm sleepy", and "I have a tummy ache".