Me and Gunnar love to go biking. This spring I purchased a bike and an attachment for Gunnar. It is the best investment I have bought! I can easily bike 4-6 miles in about 30-45 minutes and he is dog tired at the end but I'm still doing ok! I could never walk those kinds of distances on a daily basis. I highly encourage anyone with a active dog to try it out. Best energy drainer ever!