What are some activities I should have my senior dog avoid?

You may want to avoid having those longer, strenuous walks, especially if your dog isn't used to that. If they've been conditioned for it their entire lives, stick with it, but I wouldn't go on any major hikes or walks that could cause them to have bad joint problems afterward. The same goes for jumping after a Frisbee where they may be more prone to getting injured. I would avoid that.

I recommend that senior dogs avoid jumping and twisting behaviors like playing ball, which can be rough when you think about how the dog runs and then slams on the brakes and turns and twists. I'm not a fan of frisbee throwing for any dog age, as well as running alongside a bicycle. I think there are very few dogs that can do that safely without getting overheated or injuring themselves. It's not a good exercise method. I do think there are a few dogs that do that really well, but it's very rare. Again, for senior dogs, regular and moderate exercise is the best.