My Penny is about 5 1/2 months old now. I am actually driving about 1 1/2 hrs for an eval appt on Saturday for her spay and possible nare surgery. She will walk ( we also use a harness on her) but she's gets winded much sooner than her brother. But she can certainly go 0-20 in seconds if she's pouncing on her brother from across the room or the yard. Lol- we also spend a lot of time outside. Or going places. It soon becomes second nature for them. Remember, they are some stubborn babies- so consistency is key.