When duck season ended in December my lab was in great condition, just the right amount of muscle to fat and endurance to spare. With the cold winter I was able to workout inside but other than following me around while I plowed he pretty much napped the whole time.

Then spring hit and work took right off so we missed the first thawing on the water.

Finally got him down to the river for some training and he is out of shape. Gonna have to hit it hard in the moving water twice a week to make sure he is ready for those all day hunts come fall.

My GWP is kind of in the same boat.  I broke my foot so she got like almost no exercise from February to the middle of May.  I've been roading her on a bike several mornings a week (2 days on and 2 days off) and playing fetch in the river every day.  She has visually tightened up a little and her stamina has increased dramatically in the last month.

If you and the dog would be into it, check out http://www.biketowleash.com/

My dog loves to pull so when we ride so it is resisted running.  After 30 minutes on the bike she is toast after pulling my fat ass around at 10+ MPH.