I'm sorry to hear you are in the dumps Harry.. I have a few thoughts on the subject.. I dont know you.. but hope you wont mind my post..

Depression is a strange thing.. Its to me the body and mind trying to tell you something in your life is not right.. You may be trying to pretend everything is ok.. but the reality is that you cant fool yourself like you can fool others.. It could be that the job you do is completely unfullfilling.. You spend a huge ammount of your life there.. If its not a happy place to be.. then it might be time for a change.. That could be tougher to make a reality than just swapping jobs.. We all have commitments that tie us into jobs, relationships etc.. It might be that you can set your mind free by simply taking the first steps towards a change.. Maybe its deciding what you would really love to do and taking a beginner course on the subject and accomplishing a simple first step on a new road will brighten your days.

If your in a realtionship with someone long term and there are difficulties.. Maybe deep down punting is just not the right answer to other problems in a realtionship? This is something that you can help yourself with I would think.. Of course I may be way off the mark..

The other thing that comes to mind is a little more tricky as it is a difficult and willpower required area... Its fitness...
Are you a fit and healthy guy? I am not the most fit person in the world.. but I do find that excercise is a wonderful way to make someone feel good about themselves.. just knowing that you ran 5 miles today instead of the 4 you were able to do last week... The sense of accomlishment.. of doing something good for yourself.. Should help alot...

But at the end of the day.. I agree with what the others have said... There is no shame in speaking to a proffesional and getting help.. Everyone needs a helping hand sometimes.. thats why these guys work in the field they do.. You may think you are week for going to see a counsellor but in reality you are a stronger man and far healthier of mind if you are able to take that step towards getting the help you need!

Went on a bit there.. Sorry the post is so long..