Everytime someone helps me or offers me something I build up feelings of guilt and obligation and I feel ashamed by disappointing the ones which were nice to me before.
But in reality there is no debt, no obligation at all. There are only decisions, decisions if you want to be obligated. Forced upon you by yourself and the principles you want to stay true in your life.
Do I follow my love? Do I follow my belief? It's you, who decides, nobody else. As it is your choice, as it is your responsibility, shaping up the life you will have, shaping up the life you will show.
We often think we must responst to something given by giving something back or to act in a specific way because of the way we were treated before. We feel debted thus forcing something upon us. But you alone decide who you want to be, what you want to stand for and what you want your life to mean for others.