Have you heard it's important to listen to your body? No? Have you been living under a rock or something?
Okay, so you've probably heard it somewhere, and even if you haven't, you most likely agree with the statement anyway. You body is the home of your mind - soul, spirit, whatever you like to call it - so it makes sense to listen to what it has to say. If your body is in pain, it tends to tell you about it, and you should listen. If your body is hungry and signaling it to you, you should listen. If your body is ill, it communicates it by showing symptoms, and you should listen.
But listening is not enough. You should also do something about it.
Now don't get me wrong - some discomfort you feel in your body is the so-called "good pain", for example the feeling you sense in your muscles when you're doing the final rep at the gym. That's the kind of pain that develops both your body and your mind towards a better state, and you should do well to differentiate it from the kind of pain that tells you something's wrong.
For example, if you follow a special diet, you might think you can eat anything within the rules of that diet - until you discover certain elements make you feel bad in the way that doesn't develop or strengthen your body or mind. If you get nasty side effects from soy as a vegan, you should eliminate soy (you won't die from the lack of it). And not all keto dieters can eat dairy without feeling miserable afterwards - those people should consider cutting the dairy, even if it seems to be a necessary element in a keto diet. (It's not.) You can try to make your body tolerate whatever feels bad in your body, but sometimes you can't force it, and you should at least consider dropping it for your health's sake.
If four-hour sessions at the gym with heavy weights makes you feel good, then by all means, do it! No one can tell you not to. And eat cake afterwards if you feel like it. But if either starts to feel unsustainable in the long run, I recommend you consider changing something. Maybe you could try alternating weeks with heavy training and cake and weeks with light jogging and vegetables. See if you'll feel better for a longer period of time.
Last and not least, the most important thing in this entire article: regardless of all I just said, you're allowed to make your body (and mind) feel bad, in pain, and miserable. You're allowed to neglect your health, if you so chose. Absolutely no one can stop you. Not me, not some random people who are not you. You and you alone call the shots.