I don’t get it. You know, people who say they’re so exhausted and then try to gather up the energy to run 5 miles. Look, in my opinion if you feel tired there’s a reason. You might have worked out too hard and your body is still recovering from the workout. Did you shovel a bunch of snow? Did you not sleep well?
If you feel tired and fatigued, the body still needs to recuperate. Sure you can do a light and quick workout, just to get something in, but running for miles or lifting as heavy as you can will just dig your recovery into a deeper hole. Take an extra day off and see how you feel tomorrow.
Then, and only then, if you feel strong and ready to go should you workout. Working out while fatigued is just asking for trouble. Not just injury, but it could also lead to overeating.