It is only human to miss workout days and schedule because of sudden work deadlines or holidays and such. Without beating yourself up over these missed days, what you can do is accept that it is okay to miss a day or two. Many people recommend the 80/20 routine, where you accept that for 80% of the year you will eat healthy, workout regularly, and stick to a healthy lifestyle. For the remaining 20%, it is okay to slack off and be human. Once you accept that you cannot be working out 100% of the time, you will feel a lot better.