My 4 year old niece adores horses.
Except from brushing, giving too many treats and giving kisses, she enjoys riding too. I've been letting her ride only with both of us in the saddle - Candy is 16 hands tall. And my little niece never wants to get off, although I know it couldn't be comfortable to her, as the saddle is too wide for her and she doesn't have enough place with me up there.
I've been teaching her how to stop and turn the horse and she's so happy cause she can ride a horse 'by herself'.
What else could a child that young do? Candy is wonderful to her and she behaves perfectly. But, you never know, something might scare her and that wouldn't be good.
And when do you think she could ride alone in the saddle, with me leading a horse?