Therefore, I have to constantly force myself to exercise. I don't like it, but I do it. And it becomes a repetitive off and on pattern (a few months in the gym, a few months off). But believe me, I'm trying...
How can I make it stick? Or how can I be one of those people who loves working out?
When you experience sparring (i.e. "rolling") for the first time against somebody that knows what they're doing, you feel entirely helpless. It will make you crave learning more technique. Then you become the one making people feel helpless on their first day, and it's just a wild experience. It truly becomes a super power.
It's so beneficial because you're not only exercising. You're making friends, connections, and learning a valuable life skill (as well as some humbling life lessons).
What I did was to stop considering "exercise" as a distinct activity at all. Mostly, I started commuting to/from work by bicycle. In my mind, I'm just commuting. Secretly, I'm exercising for an hour every workday. Replacing your daily car commute with a bike might not be your thing, but the principle holds -- make exercise an intrinsic part of something else that you need to do anyway.
Also, keep in mind that if your goal is just general health and fitness, you don't need to do that much. 20 minutes of moderate exercise most days of the week will get you there.
Example, I have certain weight lifting goals that I want to meet so I go to the gym to work toward them.
Bottom line, decide on a goal for some activity that you like that involves going to the gym. That will be your motivation. Lifting weights over and over seems pretty stupid to me but once i add a goal it changes everything.
Look into joining a triathlon competition. It really gets you motivated to at least get in shape to complete it.