I agree with shygirl26 - if you can't stand your job, then try to change it. Even if it takes a year of looking before you find another one and can finally walk away from the bad one, even knowing that you're taking steps in improving your life will be a massive mood boost.
I used to suffer with depression, but learnt when I hit absolute rock bottom (just over two years ago) that the only way out is to fight. If you think "oh I can't be bothered to go to the gym", physically FORCE yourself to go. The first few times will be the worst, it's a constant battle against your body, your mind, your soul, but it CAN be done if you want it badly enough. Once you realise and accept that it's the depression which makes you feel tired (i.e. your brain) and that your actual body isn't tired, you can start to push past it.
It is such hard work, and it will drain every ounce of energy left in your body, but if you want anything bad enough then you can do it. I managed to overcome depression through sheer force of mind, I've never had meds, I only saw a counsellor for 6 weeks before I hit rock bottom, made a load of massive changes and decided I didn't need his help... you need to seize any moment of clarity when you sit and think "Why am I like this? Why can't I do this? I know I can, what's stopping me?" and just go. I was the weakest person in the world when I made the break, but it makes you so so strong in the future. You need to decide what you think your life should look like now and do everything you can, small bits at a time, to achieve that. For example, I've always wanted to be a teacher, but my parents made me do a "real degree", so I quit and had to face the wrath of my family. It was crap, but it was MY crap, I was in control of my life for once. Then I wanted confidence, so I got a job working abroad for a bit then started doing Kick Boxing. Then I wanted to re-establish the social circle I lost years before, so I organised a big birthday party for myself and made sure everyone came. Little bits at a time, each one building confidence in yourself. The longest relapse I've had in the last two years is three weeks :) I now lead the life I always wanted, and actually, it's better than I ever thought I deserved.