I have a 5 month old female Toy Fox Terrier named BELLE, you just wind her up and let her go.  She is very playful and has lots of engery.  I am in the process of training her and she is doing well.  She has learned to sit, lie down, and learning to leave it.  She does pretty well on walking on a leash until she see  another dog, then she wants to take off.  She still does not come when called, she thinks we are playing with her when we call her, so she comes so far and runs.  She is very loveable and has a personality of her own. 

Bertha

 

For being only 5 months, it sounds like Belle is doing very well !  I have 6 ( yes, count 'em 6 rat terriers) and have found that tiny pieces of cooked chicken works wonders in getting them to come right to me when called.  I just put the chicken in a ziplock bag and keep it with me while working with them. Eventually you won't need it any more. :-)