Counting Consecutive entries

Hi
I am creating a spreadsheet for health promotion for my clients
I want to track consecutive days without various habits eg. smoking
I have a column where the client enters the number of cigarettes smoked and I want another column to show consecutive days without smoking
I am currently using this formula
=MAX(FREQUENCY(IF($Z$7:$Z$70="Zero",ROW($Z$7:$Z$70)),IF($Z$7:$Z$70<>"Zero",ROW($Z$7:$Z$70))))

the problem is that it changes the result in previous rows
eg. if client smoked on 1st, 2nd, 3rd then didn't smoke on 4th and 5th - when they enter Zero on the 5th it changes the result to "2" on all the rows including 1st, 2nd, 3rd which should say 0

if someone could help me correct this I would appreciate it
I am self taught on spreadsheets over the internet so I am definitely an amateur!