It is no surprise that exercise is imperative to leading a healthy and happy life, and it is the same for our dogs. It is our job to provide activity and stimulation for them, since they cannot get a gym membership!
Dogs enjoy having a responsibility to their family and a job (agility, herding, fetch, hiking, swimming). Many owners underestimate how much exercise their dogs actually need. Many times, running around the backyard hardly offers enough exercise. Providing adequate exercise gives your dog a positive outlet for pent-up energy and frustration. A lack of exercise can lead or attribute to behavioral problems such as hyperactivity, anxiety, and excessive barking, digging or escaping due to boredom.
Mental stimulation is just as important as physical exercise, just as with people, an idle mind can cause behavior problems. When your dog learns a new behavior through problem solving, he gains confidence. Stimulation can be added through structured play (tug or fetch), treat dispensing toys and puzzles, sport games, hunting games, training, teaching tricks, etc.
These activities are wonderful way to exercise your dog on rainy days.
If your dog is not used to activity, increase the amount of time slowly until he is more conditioned. Pay close attention to your dog, many dogs will continue to play or run even when they are tied.