Different exercise

So, I ran out of time to exercise at home today. I was quickly approaching 5pm with no exercise done - panic set in. I was visiting my sister and she has a treadmill. I usually do my elliptical because I have bad feet and knees. But decided I was in a pinch and gave her treadmill a try. I was totally shocked at the different muscles it used! I hope I can walk tomorrow! I think it's good to shake up the exercises - muscle confusion. I've also been worried about getting enough variety in my food. I've kind of found the foods that work for me and I stick with them. Any feedback on that?