Our experiences has been that the body is smarter than we give it credit for. There seems to be something innate that gives us clues as to whether we should or whether we shouldn’t. The trick is learning when to back off and when to go for it.
Here is a general rule to follow: Always warm up thoroughly before you make your decision.
It is much easier to make a correct decision when everything is flowing. Some of the best workouts happen on days when you think you should have stayed in bed. Conversely, if after warming up you still feel like you should still be in bed, well, maybe you should. Risking the consistency of your training by doing something your body was unprepared for is never worth it.