I want to label specific cells with numbers in a sequence

Hello,

I am trying to write a script that has the below functionality:
- From top of sheet, check cells with a value in a specific row
- Replace first value with a 1
- Continue down sheet, checking cells for value
- Replace next value with 2

So on and so forth.


This would be an example of what it would do...
Before script:
Thing 5 He said, woah!
Thing Isn't that crazy?
Thing You guys are gonna help, right?
Thing 10 And then he said, what?

After script:
Thing 1 He said, woah!
Thing Isn't that crazy?
Thing You guys are gonna help, right?
Thing 2 And then he said, what?