Break enough promises to yourself and you stop believing your own plans.

Self-trust works the same way as trust with anyone else and is built from the same material. Each plan you announce privately and abandon teaches you that your plans are provisional, and after a while you stop taking them seriously enough to start. The damage is not to your character but to your ability to believe your own intentions.

Make one commitment small enough that failing would be strange, and keep it for two weeks. Rebuild the credit with things you can definitely do rather than things you would like to.