Always my best

I do my best in all that I do. No matter what it is and who it's for. I realize everyone isn't like that, which is fine. I realize I tend to go overboard at times which I don't intend to do, it just happens. I don't think that's always a bad thing. Someone recently told me that people don't do unselfish things for people. There is always an ulterior motive, making ourselves feel good for doing it. I was quite taken aback by this and it's been stuck in the back of my mind. Is it true? I certainly didn't cradle my neighbors sweet puppy as it died from getting hit by a car for my own selfish feel good moment. I just did it like a lot of other things I just do.