This is totally normal and should be expected. We can’t do anything about the past other than re-commit to following the precept in the future. In the moment you realize you have broken a precept, reflect on what happened and determine to follow it in the future. This is why many people recite the precepts in the morning and evening each day. This has the double purpose of reminding us to follow the precepts as well as knowing that we are starting with a clean slate.