Why do we sabotage oursevles?

You know who you are. When you say

"I'm cutting potato chips out of my diet," you binge on nachos.
"I'm going to pay off my debt," you drop a bunch on a credit card.
"I'm going to clean my house," you promptly leave the house for the day or plunk down and do anything but clean.

Or how about,
"I'm going to stop tearing myself down," and the first thing you do is find fault with yourself.

Why do we sabotage ourselves? Has someone convinced us we are supposed to fail? Are we afraid of success? Are the goals so lofty we've set ourselves up to fail? I do this and it boggles me.

Today I am going to focus on not sabotaging myself.