Irine Yu pointed me to the speech delivered by Intel Excellence in Teaching awardee Dr. Josette Biyo:

When your job becomes your mission, your primary concern is giving your best in everything you do. Knowing that you have contributed
significantly towards the creation of a product which can make a difference in your company and the larger community is reward in itself.

We can make a difference no matter who or what or where we are. If we know _why_, then the _how_ follows. =)