Answer: overtime
Explanation: A fulfilling career will have a work schedule that leaves the student time to relax and do other things he needs, like working, playing with his/her band, doing sports, or things like that.
So a fulfilling career will nor require consistent overtime work (sometimes the overtime work may be a good aspect, but the consistency of it is what generates some problems)
The complete sentence is:
"A fulfilling career will have work schedule that does not require consistent overtime work"