what are the goals you have in mind? What makes you question his condition/ or exercise boundaries? at 7 yrs.. you may just want to consider lengthening the walks/swims, and upgrading to a higher quality food and possibly control the amount. There are only a few reasons to have an older dog in peak physical shape.
Do not go where the path may lead.. Make your own path and leave a trail.
~Ralph Waldo Emerson~
Those that matter dont care, and those that care dont matter..!!
You're not beaten when you lose, you're beaten when you quit..
"He grew into a forty-eight pound, steel-muscled song of war, which ran, diminuendo, from a heavy chest and head to a neatly tapered tail."
*John Tantor Foote*