Specifically failure of our past.

By that I mean obsessed about our failing, about the opportunities that we missed, and the roads we did not take.

Jealousy of those who were able to carve out a good life for themselves (partly justified when those posters who do have a successful play dumb about why their life is going well), envious of those who had fun in their past, and bitter towards our own failings.

Because every time we see someone doing well it is like a kick in the guts. It's saying to us: "Look how much you suck.".

And then we think about the past. What could we have done differently? I wish I'd said yes to that party. Dammnit I think she might have been interested in me.

We think those thoughts over and over again. We think them so much that we do not think about the present, about the now. We don't think about how we can improve ourselves for the future.