"Successful people are always looking for opportunities to help others. Unsuccessful people are asking, What’s in it for me?"
Brian Tracy
Spending some time trying to help another person is normally not a big effort. What could 15 minutes to respond to a serious mail or survey from a student mean? (I insist on the serious side of this, you won't be doing anything else if you responded to everybody ;-) )
What usually happens when you make the little effort is that you get more than compensated for the interaction. Maybe not today, but you will for sure.
One example? A student asked me a couple of weeks ago about Translation Memory tools and utilities. I needed to help a client to process a huge +500 pages document that could not be handled by his processing tool. I immediately remembered the okapi (http://okapi.sourceforge.net/) utilities and the rtf splitting feature. If I had not responded to the survey a couple of weeks ago I would probably have spent much more time resolving the issue.
