I also have a dog, a beagle who is so funny and a great companion. I think play is a wonderful idea and a good place to start is coloring books. I loved coloring as a child and I still do. Get a big box of crayons and pencils. Don’t limit to just adult coloring books, the kids’ books are still fun and will lead to more ideas for fun. Not sure who said this, but it is so true: “You don’t stop playing because you grow old ; you grow old because you stop playing.” Sounds like Mark Twain.
ElderChicks 
It was George Bernard Shaw who said it, and he was so right. We also had a beagle: Spot (of Blessed Memory). They are definitely the funniest dogs. Spot would be sitting up alert near the door whenever we came home, but her warm imprint was always evident on the forbidden sofa. She also hid things (like salt-water taffies) under our pillows. Love the coloring idea!
I color greeting cards for a woman who supplies them to nursing homes in the area. She sends out the printable cards via email, we print them out and color them and return them to her for delivery. I bought a new set of markers just to do them. It’s fun and very calming, plus I feel I’m doing some kindness to others. So play can be beneficial, not only to you, but to others as well!
Beautiful!
What a great idea! Win=win!