I've had that experience too. It feels good, helping people, for whatever reason. For myself, I like feeling needed, or like I'm able to do something for others. I guess it makes me feel more confident in myself, that I have the ability to improve things for others, even if only in a small way. But then, when you realize that those people have no actual appreciation for you, it's a horrible feeling. I wrestle with it a lot, knowing that you're not supposed to help people wanting something in return and that you should just be satisfied that you helped them, but at the same time, it's not so extravagant to just want to feel appreciated and liked.

Why do you help people? What would you have done with your time, otherwise? If you were to put the energy you used helping them into yourself, are you clear on what you would have done? Often when I'm sucked into doing things for others, it's because I'm not clear on what I myself want or need at that moment, so I'm just using other people as a distraction, even when I go to great lengths to do things for them.