Take heed, going from riding regularly to just doing walking is not going to benefit this horse either. Do lots of transitions. Walk trot, trot walk halt, backup walk, walk trot, trot canter, canter trot walk, trot, canter, walk, etc.
As soon as she is nice and easy going let her continue and then transition again. It'll help to rate her speed so she isn't strung out, so long as you transition properly.