I sure understand your dilemma. The aging process deals differently with each of us. My husband just turned 70, and I will be 70 in two months. He has been deteriorating for a few years already, and can barely keep up with the firewood project. I had to make my garden smaller so I could manage it by myself. I also splurged on an electric lawnmower and an electric trimmer (both battery operated) so I can take over more of the yard work as needed. I have a great deal of knee pain due to arthritis, so I may be nuts to even consider taking over more of the outdoors chores. None of my usual tasks are going to go away. But, as many have pointed out, hiring professionals is very expensive. I do hire a teenage boy to help out now and then when I really need another set of hands...or good knees...for a task.
I really only have the one garden, which contains everything I don't want the deer to eat: berries, vegetables, flowers, lilacs. On two sides of the house I have four small areas I call "flower beds," some of which are in decent shape. One of them is quite the mess, but it's not high on my priority list to fix it up.
RE: When Gardening Becomes Overwhelming - by Sunscape