If a post shows up on your Facebook personal profile that you want to share on your Business Page, you can share the post. This video walks through the steps.
If you can control where the post goes first, put it on your Business Page. Then share if you want to your personal profile. That way the share builds Engagement on your Business Page. Facebook looks at Engagement when they decide how many people to show your posts to. The more Engagement, the more people see your posts.