My dogs are fit all year round. They are out hunting something every day . Throughout spring and summer on dykes , river banks for rats etc round farm buildings or just in woods chasing squirrels. Both Lurchers and terriers . Probably fitter on the summer with long days, light nights. Even local playing fields with a few rabbits round the edges. Not full blown hunting but something just to open up their lungs. There is no excuse for a dog to be out of shape no matter what time of year especially the terriiers