You don't have to do the treadmill. Try the stair machines, stationary bicycle, or whatever else is available to you. Or rather than running on the treadmill, try walking at a fast pace with a steep incline (as steep as you can manage) - it's great for your butt and the incline really ramps up the workout. Or try running outside one day a week. Or try jumping rope--that's also a great cardio workout. Or bicycle outside (if you have a bike) or swimming (if a pool or lake is available to you, this one of the best cardio workouts you can do because you have to hold your breath while you do it). Go hiking (especially if you have some hills nearby).
And you never know, the treadmill might grow on you. I HATED the treadmill when I started and I avoided it for months, but now it is my favorite of all the cardio machines. I like it because it sets the pace and all I have to do is keep up. I like to change up the pace, do sprints, add an incline, etc. With the elliptical, I have to push myself and I just use the same setting until it is struggle to move my legs, then I lower the setting. It's a great workout but it gets a little dull.
Also, I don't see a dire need for you to change up your routine so long as you are continuing to make progress with what you are doing. I am almost at my goal weight, so my progress is a lot slower, hence the pressure from my trainer to change things up a bit. And, you know, I might sound like I have my act together, but that's only because it's so much easier to give advice than to follow it. If you read through the exercise threads, you'll find one from me whining about not wanting to change my routine and looking for a validation to keep doing my same routine over and over again (to my dismay, I got the same advice I'm giving you

).
- Barbara