First off, you going hiking is about you, not them. Hike your own speed. I once hiked with 3 other people who were all much fast then me. I gave up the middle of the second day trying to keep up. I just walked my own pace...alone in the solitude. It was actually very relaxing and enjoyable. They would stop at major intersections or other random places and wait for me. I took lots of pictures...and they enjoyed the pictures afterwards.
If your kids are too worried...tell them to stuff it! You could also make them buy you a SPOT, or even two two-way radios (one for you and one for the group you are in). That way you can call for help, and they can know where you are.
If you aren't enjoying yourself, something needs to change. This is suppose to be enjoyable.

This last July I passed a group of 6 seniors. They all looked over 60. Some looked 70. Good for them! Hopefully I will be there as well when I get to that age.