Just because you ‘don’t have anything to be depressed about’, doesn’t mean you’re not depressed. There are many causes for depression, not just circumstances/life events.
I know from first-hand experience how annoying (albeit well meaning) being told to ‘cheer up’, ‘pull yourself together’ or ‘count your blessings’ when you can barely crawl out of bed on a morning, or when you sob your heart so long you have no tears left yet you don’t know what set you off.
There are many things you can do to help yourself feel better, many of them already mentioned above. But first go to your GP. Tell him how you are feeling. He will be able to help. Don’t be averse to taking tablets - there’s a chemical imbalance in your brain, and whilst there are things you can do that will help, tablets can give you the lift you need to move forward. Your GP can also signpost you to places that may be able to offer support. Don’t be afraid to ask for help.
Then there’s the other stuff - the stuff that, right now you really don’t feel like doing – but it will help. Exercise – a walk round the block or the shops, if that’s all you feel like doing, but it’s a start. If it’s sunny – bonus!!! Try and eat as healthily as possible. And make contact with your friends and family – even it’s a 5 minute phone call, or popping round for a cuppa – ask them what’s happening with them, take your mind of things. If you don’t feel like talking much, or you’re feeling particularly down, meet friends and go see a movie – very little talking involved, you’re out of the house and you can get lost in a film.
But most of all, don’t beat yourself up for feeling the way you do, even if you feel you have no reason to.
Big hugs and good luck