I warn a lot of my friends who's children have come late to parenting, not to over-commit themselves to childcare. Much as we adore our grandchildren, we often take on responsibilities in our late sixties and seventies that a generation ago we would have been doing in our fifties. There is no comparison in energy levels. I felt at my best in my fifties. Having got through the menopause I had a huge surge of energy and studied and qualified for a whole new career. I still do some work, though reduced through choice and I still love it, I have a very active life with going to the gym for aquarobics and Pilates classes three times a week, lots of lunches out with friends, WI membership and I help out with child-minding in emergencies but not with a regular commitment. It works well for me but I have friends who are permanently exhausted, at the beck and call of their adult children, expected to help out with child-minding to the extent of a full -time unpaid job.
Adult children make a big thing these days of having a career and seeing the world, or 'having a life' before settling down to reproducing in their late thirties and forties. What they don't factor in is their own parents energy levels. When child-minding is an occasional affair, the relationship with the grandchildren is lovely. We can be more relaxed and more tolerant, have fun and share treats, when it is not our daily norm. We are not the regular disciplinarians, as we would have to be if this was a daily undertaking. It feels lie a win-win situation.