"I definitely still have a little bit to go," Castro said. "Hitting, I feel pretty good right now. I'm still working on easing into squatting a little bit, and my running's coming along pretty good. I've got some time still to go, but I can tell I'm getting closer with stuff like this today."
Castro, who hasn't played in a regular-season game after tearing ligaments in his right knee, will go to Florida within the next few days to continue rehab.
"It's our Spring Training site, and they have some staff down there," he said. "That way, when the team's on the road, I can still get my work in every day."
Castro said that hitting on the field is a milestone in his recovery process.
"You take things like this and you use them to kind of help push you through the tougher parts," he said. "Any time I can do something like this and really experience the progress I've made, it's real positive."