It is extremely important that you do not over exercise your puppy. Puppies are very active and require exercise, but you need to know how much is enough. Too much activity or exercise can have serious negative consequences for your puppy from heat exhaustion, heat stroke, and heart issues to bone spurs and hip/joint issues.
For a Finnish Spitz, it takes 2 years for the growth plates to finish growing and fuse correctly. You should not begin serious training for performance events until after 2 years of age. Similarly, you should not take your dog for long walk, runs, and hikes until after 2 years of age. Whatever you are doing, at whatever age for the dog, always provide the dog with fresh water and keep a close watch for signs of stress in the dog.