Confidence grows when your memory has enough evidence that you keep promises to yourself.

Confidence is memory, not personality. When you have a long record of doing what you said you would do, your mind stops arguing about whether you will follow through, because the argument has already been settled by evidence. When the record is thin, no amount of encouragement fills the gap, because you know what the file actually contains. The fix is boring and completely reliable.

Make promises to yourself small enough that you will certainly keep them, then keep them. A ten minute commitment kept for two weeks is worth more than an ambitious one abandoned on day three. You are not building the habit so much as building the evidence.