Depression is winning

I've never posted one of these before. I just feel like I need to do something, anything to jolt myself out of this numbness. I can't seem to break the cycle. I've gone through this so many times in the past. At one time in my life, I thought I was beating this disease - but it came back. It always comes back. I make progress, and it really seems like I am going to finally break this - and then boom! there it is again. And it doesn't really take much to bring it back on - just some kind of interruption in the cycle of my life when I'm in a progressive trend. And of course, it always brings the poor diet and exercise habits with it that cause me to gain weight - and lots of it (to the point where I am now obese again after I had lost a lot of weight) - which exacerbates the problem to something that seems wholly insurmountable. How do I end this stupid cycle? I do I get out of this funk I'm in? Especially when it all just seems like an exercise in futility now.

I can't seem to even get my mind going toward some semblance of motivation toward fixing this problem. I've tried medication is the past, and it just didn't help. It made me feel worse. The only thing that has ever helped was exercising regularly and living better. But it's the getting to the point where I am actually making the motions to get to that point that I seem to be stuck on.

How do I get over the hump? How do I convince myself that it's worthwhile even though I've tried and failed so many times in the past?