There are times where I just want to lay down and sleep, curl up and cry but I know that all is well in the world and I have no reason to do that.

Remember that you have physical needs as well as emotional needs, so perhaps wanting to lay down and sleep is actually what you need. I'm thinking of the kind of general "under the weather" that resolves itself after a good night's sleep. Physical tiredness can impact on emotions too, so feeling a bit weepy when I'm tired isn't uncommon for me.

Pushing through is great, but so is being kind to yourself. Are you pushing too hard? It is perfectly OK to allow yourself to be a little down (either physically or emotionally) from time to time.