Just because you have 'nothing to be depressed about' doesn't mean you're not depressed.
There are several causes of depression, not just circumstances/life events.
And just because you have 'nothing to be depressed about' does not mean you should belittle your feelings in anyway or feel ungrateful or guilty.
I know from firsthand experience how annoying (no matter how well intentioned) platitudes such as 'pull yourself together' and 'count your blessings' can be, especially when you can hardly get out of bed on a morning, or are sobbing your heart out til you've ran out of tears and you don't know what started you off.
There are things you can do that will help you feel better, but i understand the thought of doing any of them may feel like climbing a mountain, no matter how simple they are.
So, first - go to your GP. Explain how you are feeling. Your GP can help. I was very resistant to take tablets, but when i finally gave in and started them the difference was amazing. Basically there's a chemical imbalance in your brain - an whilst there are outside factors that can help, an initial boost maybe all you need to pick yourself up.
Now the other stuff - the stuff that makes you want to run and hide right now - is the stuff you need to try and start doing. Exercise is good...a walk to the shops or round the block, it's a start, and if it's sunny, it's a bonus! Try and eat heathi