yes, they do slow down as they age. It's usually after one year of age, tho. Rosie liked to climb trees when she was young, she hasn't wanted to climb in the last couple of years. Lil Squirt liked to climb last summer but hasn't much this last fall.
You can put him into a room that's beardie proofed, such as your bathroom,that might be easier than the bedroom, and let him run. They like to explore. Squirt will be 2 years old on June 18th and she still seems to like to get herself hidden in our bedroom, which is easy for her.