Lee, I got my feet wet around 4 years ago when suddenly my wife and I (both in early 50's) suddenly found ourselves with a small child and us in charge. I loved photography in high school but due to college and work afterwards never had time again, then my wife's grandma moved in with us for about 3 years, two years off then grandkid. We are both tired too. However, that child put a spark in me to prove to myself I could make "that" picture of a kid EVERYONE would look and stare in amazement at. It took me about 6 months and alot of luck, but I did it. Since you said you have a grandchild around too, get the camera out and start following.....it hasn't cured the being tired, but it sure has given me a lot of fun and satisfaction.....and made we wake up to the world around.
I recommend a 35mm to follow the kid.....tried 645.....if they are movin' I gotta' have autofocus now!