Animals like children are powerful source for inspiring and understanding play. This probably one of the main attraction of keeping pets, while our culture discourages us from roughhousing, climbing, and playing tag with our peers a dog or cat can take us back to a child like state of play quickly and nobody looks strangely at you for playing with a lure and cat, or playing tug of war with a dog.
If your interested in bringing more play into your life spending some time with animals is great way to do it.
In addition it is likely true that just like being in nature is inherently good for our psyche so is the presence of animals. E.O wilson has coined the term biophilia to describe our attraction to other animals and living things and it is the case that humans are unique in the animal kingdom in our propensity to keep other species among us. There are many examples of commensualism in animals like mixed herbivore herds, birds which spend of their time on the backs of big herbivores, or ravens which alert wolves to carcasses, and play occurs across species too but no species seems as inherently fascinated with other animals as humans and none create companionships and play relationships with so many other species.
If you have a dog or cat or other animal spend some time playing with them, if you don’t there are always animals in local animal shelters who would greatly benefit from an hour of your time playing with them and you would benefit as well.
For some inspiration check out this great dog and human parkour video.