An easy way to bring some mental stimulation to your dog or cat, is to make them work for their food.
Run through any commands they know (or teach them new ones!) and reward them with a little bit of their regular food when they do it.
Dinner-time enrichment can be as simple as placing some food on the floor, covering it with a towel, and letting them get the pieces out from under it.
There are lots of treat-dispensing toys that you can purchase, that let little pieces of treats or kibble fall out when your pet pushes or rolls it around. Make your own by cutting small holes in an old water bottle. (If your dog is an aggressive chewer, make sure he’s not breaking the plastic into dangerous pieces.) And make sure it's not too difficult to get the pieces out! It should be a fun challenge, not a frustration.
Slowing down meals is a great way to add some interest to your pet's day, and if they tend to wolf down their food, this can even help prevent choking or bloat.