I believe the quote itself is true, but the key is not to get used up or used until situations become uncomfortable. You can't let people take advantage of you, because they will, including family, friends, and jobs their is no limit. Just make sure you are comfortable with doing something before you commit to it and put yourself in a bad situation. Make sure you are more useful than used.

I myself am learning to cherish life and my days more, spending a lot of time away from family living a piece of my dream is tough. I understand the sacrifices I've made and the people that would love to be in my shoes. Im learning to take everything as a lesson rather than a loss, because in each moment in life there is something to be learned. There are times I do tend to worry about the things I don't have and worry about where I think I should be in life. Then I remember too look back and see how far I've came, while keeping in mind appreciate the current in order to be ready for whats next. I start my days off with prayer, an overflow of thanks for the previous, the present, and the future.

I myself sometimes feel this way at times. Very grateful for my accomplishments but knowing that I am capable and better than where I am. I think it comes from comparisons to others, we sometimes compare ourselves to others and forget we all have different paths even if we set out to achieve similar goals. We have to remember everyones "come up" happens separately and in order to receive a bigger blessing we must first fully cherish and accept the current blessings. So in answering the question no you can't be neither grateful nor thankful and be unhappy.