Do you have to talk yourself into going to work everyday? Taking a shower and all the stuff that goes with it (make-up, hair, etc.)? Preparing your meals? Doing the dishes? Cleaning? There are things we all have to do that we don't like doing and we just do them on autopilot. Make the gym one of those things. I work out every day, period. There's no debating, arguing, or convincing myself. I just have to do it, just like I have to go to work every day.
It also helps to think of the gym as "me time." I have a special iPod playlist of favorite songs that I listen to at the gym and the only time I'm allowed to listen to those songs is at the gym. During the rest of my life, I am always doing something for someone else. Even when I'm watching TV, I'm multi-tasking (paying bills, folding laundry, etc.) At the gym, I'm zoned out in my own little world, listening to my favorite music, doing something for me and me only. No one else gets a piece of me then.
If I have time, I reward myself at the end of my workout with 10 min in the dry sauna. I

the dry sauna. I also reward myself with massages every two months. Maybe you can find some little reward for yourself.