That's what I am.
One who helps out when asked, sometimes without asking and usually regrets it either way.
Now, I will admit that when I help off my own volition, if the person didn't ask for it, I'm putting myself out there for complaints or down right ire of the person I was helping.
What does bother me is when someone specifically asks for my help and I follow through only to hear complaints and anger. I don't even expect thanks at this stage in my life. I'm helping because I want to or I know it's the right thing to do. Not for recognition. If I majorly screw something up, I can understand someone being upset. When results are as expected however, it is annoying to say the least to be where the anger and resentment are targeted.
So why do I keep it up? Because somewhere deep down, I believe the best in people. I believe I can make someone's life easier. I believe I can make a difference and be a positive influence. It would be a sad day if I don't feel that way.