When you set expectations high people will expect high expectations from you all time. If you give someone present everyday they will want it everyday and the day you don't bring them a present they will be upset. Your boss will make you do more work because he knows you are capable of it even though you may get paid the same as other employees. Now if you were to be an average worker and do a little more work you will be praised.
This guy explains this much better, http://mbainexperience.com/2011/10/29/want-to-be-promoted-stop-working-so-hard/.