Its so much on our wish list to do one of the heli-hikes. However we are in our 60s and in general good health, but not what we would call athletically fit!!!!!. Just wanted to have some feedback from similar visitors to see if we are being realistic in attempting a glacier hike?

A typical heli-hike is similar to walking on snow. You are not climbing or having to navigate over anything. If you have walked on snow, I would say you should be fine. If you haven’t but do walk a fair amount, it should be fine too although experiencing the snow under your feet may be a novelty that you may need to adjust to first.

Will you be doing this in Franz Josef, Fox or Aoraki Mt. Cook? If you'll be doing the glacier "heli-hike" on Franz Josef, they'll give you crampons that will grip the ice, and trekking poles. The guide will cut a path for you, and you'll walk more or less single file behind.
https://www.franzjosefglacier.com/ou...ier-heli-hike/
You can read reviews of this on TA (read the ones that say "heli-hike"):
https://www.tripadvisor.co.nz/Attrac...Wahipouna.html

The heli ice climb is a different story. I don't think you'll want to be doing this:
https://www.franzjosefglacier.com/ou...eli-ice-climb/

If you have doubts or questions, call them, ask about the difficulty--or ease--of the heli hike and about any other lingering thoughts/concerns you might have. It's cheap to call New Zealand. 2 cents a minute on Skype.