How does the feeling of being useful to the client, can it be a powerful motivator for the employee?

Definitely yes. If you really are dedicated employee you would feel better as a person too. There's no better feeling to have meet all your clients desire and expectations if you are a well driven employee.

thanks!

Yes, it tells us where we lie in this competitive world .And when it rewards us with handsome perks and promotion we eventually attain confidence.

Absolutely , there is nothing more important than self respect, especially when you have achieved something, that the time to do it again. 

Thank you for calling for the answer: The feeling can be useful to the client through the perimeter of his work and what is going on around him and is a strong beneficial to the employee by recognizing what is going on around him

Yes its true and it gave me more power to do more work

 because it gave you and our cleint add value that will be  satesfied needed and in the least have a re respict from your self  and from  your customers 

Thank you for the invitation

Agreed with colleagues

Sure,it is

at least someone is appreciating your work :)