second day syndrome
The degrading probability that you'll return a workout regimen after taking a day off.
The day after break from working out, the memory of going to the gym and not going to the gym are both fresh in your mind. Not going to the gym is a slightly fresher memory so I’ll say that getting a workout in has about a 40/60 chance of happening: second day syndrome. On the next day the probability drops to 30/70. Add that to the guilt of not having gone now for 3 days and you have a recipe for disaster.
Second Day Syndrome
The condition whereby on the second day of being back at work/college after a holiday and/or long break you are a lot more fatigued and generally more unhappy than you were on the first day of being back at work/college.
I was feeling a lot better being back at work yesterday than today, must be second day syndrome.