Excess is a funny thing.
The line between enough and too much is beyond blurred - I swear it moves.
Food, drink, exercise - whenever I think I know my limits I'm constantly reminded that I am, in fact, a fool :)
Food - well, that's a relatively easy one to get a handle on. I always think I'm hungry. It's true. Mr. Diva can attest to that. But I'm not (unless I'm cranky, that's a sure sign of hunger. I'm like a baby that way). So I can reduce the likelihood of eating to excess if I simply stop and take a breath. Wait a few minutes to see if it's hunger or not, and move on from there.
Drink - well, again you can confer with Mr. Diva on this one. I am apparently unable to pace myself. I drink my drink. My glass is empty. I refill my glass. I drink my drink. My glass is empty. I refill my glass. You can see where this is headed, right? Particularly in a large social setting, where I'm having a great time talking to people I like - I completely lose track. Then, about 20 minutes after we get home, it all hits and I'm miserable. Solution - when I think I want just one more, STOP.
Exercise - now this is the toughest nut to crack. Who amongst us doesn't feel that if some is good, more is better? I mean, really. If I feel great running 40 miles a week, I'll feel better running 50 or 60 (I really did feel great when I was doing 60 mpw, btw). If lifting 3x a week is good for me, then why not lift those 3x a week and do skill and accessory work the other days. Oh, and run. Right? Come on, who's with me here?? Beuller?? But the truth of the matter is that overtraining is just as undesirable a form of excess as eating till you're stuffed or drinking till you're drunk.
Too much is too much. Period. Regardless of your poison, if it's more than you need - it's simply gluttony.
Put down the fork, have a glass of water and take a rest day.