Cool idea. But it probably won't work out the way you might think.

Here's what it seems like to me - as you age, people have wildly different levels of health. Some people are in awful health, and can't do anything. Others are fine. Seems like 8 out of 10 older people (over 70) are out of commission because of a major health issue, or are just about to have surgery, or are recovering from surgery. Or have to take care of an ailing family member.

So the likelihood that you'll be "in sync" is low.