Am I overdoing it?

I am 62 y.o., and was diagnosed as Type II 3 years ago. Up until this year, I have always had a "desk" job, but in August, I started work as a parapro for kindergarten and first grade special education. I may have signed up for more than I can cope with. My body pain is severe. I love the job and working with these precious children, but feel that I may be damaging my body, as I am up and down all day. I feel like I am 90 years old when I leave the school every day.