Rename files under folder structure

Hi,
I have a folder structure root/YYYY/MM/file.jpg
I would like make a rule to run in all folders/subfolders until get file name and rename this file(photo) to YYYY-MM-DD_file.jpg
i try some tests with run sufolders but not success, some can help me ?
I have a folder structure root/YYYY/MM/file.jpg
I would like make a rule to run in all folders/subfolders until get file name and rename this file(photo) to YYYY-MM-DD_file.jpg
i try some tests with run sufolders but not success, some can help me ?