-e git+https://github.com/orcasgit/python-fitbit.git#egg=python-fitbit
- get an API APP key on the Fitbit site: https://dev.fitbit.com/apps/new
 - authorize your app for your account:
see python-fitbit documentation: 
./fitbit/gather_keys_cli.py <con_key> <con_sec> - write a credentials.py with the following content (of course insert your data)
 
APP_KEY = '' APP_SECRET = '' USER_KEY = '' USER_SECRET = ''
- create directory "backup" for json-files
 
python backup.py
There are lots of possibilities to improve this script and I am happy to merge pull requests. For now this script backups my data and thats what I needed.