Our breeder/kennel whom we have known for a long time & is VERY reputable from whom we got our now 6 month old SOILY from was very adamant about the 5 minute rule for exercise. e.g.- 5 minute of exercise for every month of age...if 5 months old...25 minutes of exercise/walking per day etc.. Lack of bone structure is the main reason for this. For the first 4 months I was very close to keeping this recommendation. Now I am stretching the rule a little. I now at 6 months am walking him around 40-45 minutes most times on a single walk that is mostly level most of times,every day. That's about 15 minutes above the rule.He has NEVER shown any signs of being tired & we have cold weather in the Northeast here. I know even if he shows no signs of being tired that doesn't mean he can't be over straining his joints...he just doesn't know that. What's the thought here of slightly over doing the 5 minute rule?