Does 'karma' really exist?

Sometimes I feel like my depression is my karma...maybe for not appreciating what I had before I was diagnosed. But I was only 18 and too young to sit down and appreciate anything. It's a destructive way of thinking...but I don't know how to rid of it.

I don't think you are paying for taking things for granted, rather it may be the other way around: Being too hard on yourself is a symptom of depression. You were 18... and only human. What 18 year old is able to see the bigger picture and appreciate everything they have? I didn't know many. That's just being a teenager. It takes a lot of wisdom and experience to appreciate what we have, and hard times to contrast against the good things so as to put it all into perspective. Of course, I need to be taking my own advice on this one. We all know this logically, but depression has a messed-up way of altering our reasoning skills to work against our favor (not in our favor?... eh. My grammar stinks). *hugs*

Karma that we experience this present life was already made in your previous life.
so things don't seem to make sense because you just don't remember.
In this life time we are making karma for our next lives.