Get help. Honestly, especially if you have health insurance, see a psychologist. I just started and it's a great first step.
Edit: Not directed at this poster, just at anyone who might be feeling depressed. I didn't realize how depressed I was until I talked it out with my psychologist. You sometimes just take it for granted that the misery is baseline.
For some people it could be as simple as realizing that your brain is screwing you over, and therefore you can't merely intellectualize your way out of depression. Your grey matter is (mostly) fine, but it's swimming in a soup of self-perpetuating depression chemicals.
It's all but impossible to force yourself to be happy when your brain is chemically forcing you to be depressed.
It would be awesome if a magic pill existed, but for now the most effective way to reboot your brain chemistry might just be exercise. I joined my local gym, and made myself go regularly by promising myself that I'd only ever listen to my favourite podcasts while in that building.
I'm pretty sure that's prozac (and it's relatives). It has it's own set of side effects that you may prefer the depression over, but it essentially is a "magic pill". (Depends of course on the severity of your depression).
Meditation, Cognitive Behavioural Therapy (CBT), Exercise, and Drugs are pretty much the corner stones for treating depression.
Edit: Not directed at this poster, just at anyone who might be feeling depressed. I didn't realize how depressed I was until I talked it out with my psychologist. You sometimes just take it for granted that the misery is baseline.