Ivy is a 16 month-old Lab. When it's time to go to the beach, the two older dogs hop in straight away, but Ivy has to be picked up, (the correct way I might add). she has to be unloaded and on returning, she tries to stay put, and has to almost be dragged out. Occasionally recently, she has jumped in and out a couple of times when she has seen something she wants to get at. At her age, is it reasonable to expect to have to lift her in and out, bearing in mind the young dogs development?