Sure, Denny was able to keep up with the younger dogs at the dog park, but he was definitely paying for it last night. He had a hard time getting up the stairs (I helped him halfway, he slowly made it up the rest of the way). When he did make it upstairs he was unable to jump up on the bed. I tried to help him but he made it pretty clear he didn't want help. He eventually headed back downstairs (no problems downstairs, only up them) and later in the night I heard him whining in his sleep. It's very hard to see him getting older.