What do you do if you feel empty and life gets tough including REALLY tough?

One thing I've learned is that nothing lasts forever, even the hard times. So the first thing is to remind yourself it will get better. In the meantime take care of yourself. Let yourself process whatever is going on, but don't get mired in it, or in negative fantasies about what could happen down the road. And as you move through the bad time just take it one step at a time. You don't have to figure it all out at once. Just take the next right step, and then the next right step after that. Eventually you'll be out of it.

Get exercise, spend time outdoors and get off the internet.

This going to sound totally bizarre - but it is exactly what one does during difficulty...

First of all, as they say, any day above ground is a good day.

But even having said that, everyone has difficulties in life. If I start to think "Oh man, this sucks!" and get angry....

I then start thinking of The Elephant Man. How difficult HIS life was. ANything tough I go thru pales in comparison to what he went thru in his life. So you then chill out, figure out the solution to your problem, and move on.

Not to mention you end up realizing how good you've got it.

This might sound silly but when I was going through a deep depression about the time this movie came out, this scene helped me pull out of it:

https://www.youtube.com/watch?v=qgpEdTWdfwQ

Go out, engage in activities, workout, take a walk even if you don't want to. Don't focus on things you cannot solve. Journal