My UK GK are 17 and 20, so too old for such shenanigans. My Aussie GD is 2, and I would love to be able to look after her for a day. I also know that as an arthritic 79 year-old, it would probably kill me!
I look back to the days when I had 5 children, spread over 16 years, and also fostered and child-minded for a lot of that time. We had no car, so I walked over a mile each way, twice a day, for many years with - usually - a pram, and a toddler sitting on the pram-seat. My DH worked 'continental shifts', so meal times were all over the place, and so were babies' feeds. I did all the gardening and baked several times a week. The amount of housework and washing involved was enormous, yet I seemed to sail through it all.
In retrospect I think, "How on earth did you do it?" I suppose the answer is that I was a lot younger and fitter then, but I still look back on my then-self with awe and admiration!
I just wish that I had a fraction of that energy today!