OptimalWorkHoursPerWeek are the number of hours that allows you to do a good job at your own pace while still leaving enough time to enjoy your personal life as much as you need and want.  They must also be balanced by your current demands for PersonalIncome (as affected by your WageRate) and your value of Leisure.

Or, OptimalWorkHoursPerWeek are a couple of hours less than the hours you work now. ;-)