If someone has helped you in any way of your life. You should thank them. You will feel once better when you do. If you don’t you will feel worthless and guilty that you didn’t. There are people who want to help nice people like you. I don’t think not thanking them for their efforts of saving your life will leave you all positive. Sure, it will leave you positive, but there will be some of that guilt wishing you would have done so. Mixed feelings are more the point you will feel. Give a moment of thanks to nice people who have given a chance on your life. Think about it. I know that you won’t be a loser by not doing it, but remember that blame will get ugly on you someday. Thank them. It’s the correct choice. Your life will be viewed positive, if you do!