Very good, very good, when in accordance with the Dhamma, and even liberating if kept, good householder. It's like it act-ually works, this way of guided self-blessing and honesty toward one self. And it's not at all bad kamma to break low and harmful earlier promises, for going in contract with more sublime. Such asn for today on, I will abstain from any taking of life, and give up all previous promises requiring such... taking what isn't given... fleshly misconduct... wrong speech... taking intoxicants causing shamelessness...and give up all previous promises requiring such.
more on it: Is changing your mind same as lying? Breaking promises