How can I stop being a negative dreamer?

Hi guys. I've got a problem that I've started to realize might be affecting my life pretty significantly.

It's very often that I go to bed feeling quite optimistic and excited for the next day, only to wake up in the morning emotionally drained and stressed out. I think one of the reasons is bad dreams. Not nightmares in any way, just unhappy, stressful, anxiety ridden dreams in which I deal with criticism, failure, and general unpleasant things. No intense fear or pain, just a dull and tedious malaise.

Have any of you used lucid dreaming to conquer these kinds of feelings? Do any of you have stories or tips on using lucid dreaming to elucidate negative feelings and dig deeper to find where they're coming from? Are there any other ways I can set myself up for more positive dreaming, so I don't wake up in the morning feeling like I just ran an emotional marathon? For the most part I'm a pretty positive person. I have a good diet, I exercise, and my life is pretty fulfilling otherwise. So I'm not quite sure why most mornings I have to dig myself out of a rut.