Jaimson received a raise at work and had the option to cut back his working hours from 40 per week to 35 per week. But he chose not to reduce his work hours. This is because he wants to show the leadership his hard work, association and dedication towards his work. He might want to remain in their eyes because of his work for which he has given a raise.
There could be a second reason as well. He might receive an overtime allowance on working 5 more hours in a week. He was already working for 40 hours, and continue to do so won't be a big deal for him. So he might want to enjoy the overtime.