"senior" volunteer

I went at the age of 60 and found the experience not nearly as daunting as I had expected, volunteers are generally either fit retired people or students. all there because they want to be there. We all got on very well together.
The staff are very supportive, doing their best to fit the volunteer with the project. However it's also up to the volunteer to be tolerant, adaptable, energetic, positive.
The time in Thailand (a month in Nong Khai) was comfortable and interesting, but the two weeks in the Lao jungle village were challenging, right away from my European life style, a memory for life.
Parenthesis: A little added advantage: while I was there I ate very healthily, (delicious and abundant food) lost two kilos and continued the same diet when I got home. Now down to my ideal weight!