Me and overtraining were married for quite a while., but I divorced her and have been happy ever since. Oh, she comes back once in a while beggin` but I slam the door in her face.
It's a highly individual thing. All things being equal, exercise tolerance increases over time. Beginning lifters tend to be gung ho with emotion without intelligent directing of that emotion. Usually beginners not eating right is the main thing. Learning through trial and error over time and by applying a lit match to most of the popular muscle magazines is how a lot of whom are not naturally gifted progress. Most Olympic competitors train with levels of volume and frequency that dwarfs the majority of even us more serious gym rats. But they had to work up to those levels -- over time through intelligently applied training methods and planning.