Providing examples where you dealt with disappointment is fine. How you deal with disappointment should be the point of your answer. It is one thing to have been humbled by an experience, but it is another to learn from the experience and use it as a growth opportunity. This is an opportunity to display yourself as a half-glass-full person. Use examples that reveal your ability to adapt, detailing how quickly you reacted and the logic behind your course of action. Avoid examples that reflect poorly on your performance. Describe the situation, the obstacle, and how you ultimately overcame it.

"There have been times when it proved difficult to aid those who needed assistance but refused it, or were too emotionally or mentally unfit to allow it. Those times are difficult to face when they happen. So I think the main thing I would do differently is less hard on myself that I wasn't able to help everybody universally the way I hoped to. I've learned that now, but those emotionally charged hurdles held me back a little while early on. So knowing what I know now, I suppose I'd give myself a little more self-care for those cases that affected me so. When I face those situations today, this is what I do..."