Sometimes being unhappy is okay. I've learned that when I'm sad for a reason (grief, loss, disappointment) it's better to just be sad and get it over with.
However, there are times when I'm sad when there's really no identifiable reason for it. At those times I have some "thought exercises" I do that involve sort of picking apart my unconscious thought processes and identifying the "cognitive errors" I'm making that are having me be unhappy.
I've also found that exercise works wonders! Sometimes just being outside in fresh air - either in the city, around people, or in the woods by myself - feels like it literally clears away the cobwebs. To get clinical about it, regular exercise (20 minutes 3x/week) has been shown to be as effective as prozac in treating depression. It releases endorphins and helps regulate your brain chemistry. Find something you enjoy doing, though, and perhaps find someone to do it with so you don't have to rely just on yourself to motivate you to get out and do something.
Meditation also helps me sometimes - just remembering to breathe, and just noticing where my brain is going and gently bringing it back to just breathing and being.
Good luck, dear!
