Mental Blocks

Anyone that knows me very well knows that I've always had a tough time not only with self motivation, but motivation in general. Here I am 22, on o2, and I can't seem to get it into my thick skull that if I don't change now...like right now, I'll be dead before I know it. Its the same thing with exercise. I've let myself get to such a low point physically that exercise is really hard for me, the moment I start to push myself my mind goes into a panic and I am faced with my anxiety problems. Even tho I know I am doing myself no harm, my mind starts to tell me otherwise. It makes it dang near impossible for me to get the drive to get up off my butt and do what I know in my head I need to do. I know when I don't take care of myself, not only am I hurting myself, but all those that love me, especially Nikki. I love Nikki so much that I just want to take care of myself for her, I really do. But the moment that it comes down to it, I find I lack the strength to do it. She's tried and tried to get me going, she'll even exercise with me! I don't know what I can do to pull myself out of my own head long enough to do the exercises that will ultimately give me more years with her. I've tried TV, movies, music...nothing can fully distract me enough, and I HATE it. To make things worse, when I don't do it, I mentally beat myself up. I know I'm not perfect, but I feel like I've done nothing but let Nikki down. I want to change so badly for her, for myself, but mostly for her. I just wish I wouldn't make this so difficult for myself.....