It sure is a lot of work, and people like you who recognize it ... well, that is the best reward! 
the nights awake worrying about a deliver about to happen or just after that are the most stressful for me. I get exhausted ! But i never complain one little bit...
to hold those tiny babies in your hand and watch as each one blossoms, and the personalities ... it is so rewarding. Then it never ends... you find the very best homes, and you make so many great friends, they sort of become part of your family as well because they have possession of something that will belong to you forever ! 
It is all worth it ! 
But also it is not for everyone. but for those who put their hearts and do it for the love it is very rewarding after all . 
Good luck with your 2 "teenagers" kkkk ..... 
Blessings

XOXO