You should be very careful with global variables. It is considered a better practice to avoid using global variables, updating them in different locations in the code. It should not be a problem if those are only constants, though. Usually I do it this way:
variables.py:
MY_PATH1 ="c:/something"
MY_PATH2 ="c:/somethng2"
MY_PATH3 ="c:/something3"
main.py
from variables import *
def run():
    print(MY_PATH1)
    ...
If you are working with path strings, you may also want to take a look in the documentation for the os.path module. It helps making path descriptors compatible with the different platforms, among other useful things.
     
    
import variablesthan usevariables.path, variables.path2,....