This is just for my curiosity, we're already on all the right waiting lists to see doctors, OT, physio etc. DS is 4y3m. He shows some signs of a mild disability and mild mobility issues. He can walk and run and jump and walked on schedule at 15 months but he seems to tire more easily than my older children who are now teenagers. Today we think he walked about a mile (with rests) but I think my older children could do a lot more at that age.