Is there anything I can do to ensure that my bunny will be healthy?

Well, I suppose if the toy is large then it will be fine. I like to make homemade fabric toys with a bell inside. Mine Loves it! If she likes to play, I would bunny-proof a room and run around playing with her. If not, I would go out side and she runs then run after her and catch her. They love it! Put them back to their starting point. It's a neverending game (unless she decides to sleep). I would just keep a full bowl of food in there because I don't believe in diets. ( as long as she's happy, right?) But, yeah. Just make sure you play with her and she is happy and gets alot of excersize. Hope this helped ^.^