Why try your best?

A month ago, this question pondered me while I was being asked by a superior.

"Why do you try your best?" . He assumed that our reason for trying our best in examinations like the A Levels is because of pride and "face".

However, I beg to differ for my case. I am trying my best because it is my responsibility and thanksgiving. Everything I have is a grace from God and though I cannot repay His grace, what I can do is to use the grace to do things for the Lord, according to his commandments. Furthermore, in the Book of Colossians, it says

Whatever you do, work at it with all your heart, as working for the Lord, not for men, since you know that you will recieve an inheritance from the Lord as a reward. It is the Lord Christ you are serving.
Colossians 3 : 23 - 24

I try my best....to glorify the name of the Lord.