What is it about seva that makes people dynamic versus doing office work?

Gurudev Sri Sri - See, we have to do something and we keep doing something. When we do something, we want something out of it for ourselves. Now if you do something for which you don't want anything in return, but you just want to be useful in life, that is called seva. An action for which you are not expecting a reward, but you are happy just by doing an action, which would bring benefit to others, that is seva. An action for which you do not want any benefit for yourself, but instead you want to be beneficial to others, that is seva.