When you are starting, ignore all the stuff about having to get in a certain amount of time and just know that something is better than nothing. Well, up to the point where too much hurts and you don't want to do anything the next day.
I found the elliptical way better on my knees than the treadmill, but when I started I could only do five minutes and I thought I was going to die.

But I did that and then the next day I did six. Repeat. I got up to doing an hour. It took awhile, but I never would have gotten there if I hadn't started with that five I could do.
Don't worry what anyone else thinks. Sometimes I hop on an elliptical for five minutes to warm up before lifting weights and I have seen other people do that too. Not caring what other people think is also a muscle that I work out in the gym.
