How many times have you walked to the shop, or have even driven to the local market, then ended up carrying a bag or two of groceries as you browse. If you have a large dog like a German Shepherd or Rottweiler, why not take your dog with you when you go shopping and let them help to carry the groceries? There are many excellent dog packs available at pet stores, and one is bound to fit your dog and your budget. The benefits of this activity are that your dog gets an outing, and at the same time they enjoy some exercise and a change of scenery. Just don't overload the dog, you can cause damage to your pet if the load is too heavy. Most dogs love being useful. They love to please, so why not take advantage of that inclination? Both of you will benefit from this activity and have fun at the same time. This activity helps when you go trekking, as your dog can carry their own water and treats, and maybe a towel or two. Let your dog work and earn their food, they will be healthier and happier for the experience.
If you come home from work and have little energy to spare, set your large dog up with an outdoor puzzle bottle on a length of rope. Instead of giving them their usual afternoon meal, you can take them for a few laps around the block, then take them in to back yard with a puzzle toy. You can buy a puzzle toy or make your own. A thick bottle with holes punched in it is a simple form of puzzle. The benefits for your dog are that it will take a while to get all the food out, and they will get exercise by sliding the bottle, shaking it, and turning it around. It provides valuable exercise and increases their ability to solve a problem. If it's summer, you could also put out a frozen block of beef broth that has some healthy pieces of meat and vegetables in it. As the block defrosts, your dog gets a treat, and the frozen broth is refreshing.
Dogs get a kick out of helping and feeling useful. As you do your work around the home, train your dog to help. They can hold the hose and spray the wheels of the car as you wash it. They can be taught to collect the pegs you drop on the ground when collecting the washing. Train them to pick them up and drop them in the peg basket. If you have a fire you could train them to bring in the firewood, one piece at a time. Or, their job could be to collect the mail and bring it into you (in one piece preferably). Dogs are highly intelligent and you can use their eagerness to help to your advantage. It's like having a helper with you 24/7.
The bigger the dog, the more exercise they need. Perhaps you can hire a dog walker once or twice a week to drop in and take your dog for a walk. Professional dog walkers are experienced dog handlers with references. Even a half an hour walk around the immediate area of the home is better for your dog than sitting and being bored. The other option is to trade services with a friend. Maybe they could walk your dog a couple of times a week, and you could babysit their kids so the parents can enjoy a bit of time together. Your dog will enjoy a change of scenery and won't be so demanding for a walk the moment you get home.