If I were younger, I would seriously consider volunteering for a couple weeks to help out for 1, and for 2, a more selfish desire to see a place with so much history, architecture, and culture. I give you great respect for your noble endeavors, and God bless you and the citizens of Israel.
I worked with spry 80 year olds. You do need to be able to walk some distance over broken surfaces and carry maybe 20 pounds. If you can do that, you can make it. Indeed, they’ve had many volunteers in their 90s.