Can't say I've ever had clinically diagnosed depression, but I certainly have better weeks/months and worse ones when it comes to my mood and mentality. Talking, Time, Exercise and Acceptance (the latter being the hardest by far) seem to get me by. I think this is normal life for most people.
I have some friends and ex-partners who have life long depression issues. Counselling, drugs, exercise and time seem to help them.
I'm no doctor, but you should probably go see one (or a councillor) for advice.
Well done for opening up about it too - acknowledging there's a problem and talking about it often seems to be the first critical step in the healing process.