I have read that my type of dog (BichonxChihuahua) needs approximately 20 mins walking a day. He has more than this and seems to enjoy it. He has an hour in the morning some of it off lead, playing with his friends, and three quarters of an hour in the afternoon. This is routine and he has more if weather is good. He is two and a half and still wants to play when we get home. Please some advice, should I cut his exercise down? Have I harmed him? He didn't get so much exercise as a puppy as I was conscious of him being little with undeveloped bones.