In this life, there are givers and there are takers. You most likely define yourself as one or the other. Now, don't judge yourself just yet. It takes many different types of people on this earth to make the world go round, and everyone has a different purpose and path. I do believe, that all of us are good people at the root, but society, pressure, money, power, and other things can get in the way of that and steer us in the wrong direction.
I once managed a guy named Tim (name changed). His work was strong and I considered him a key player on our team. But I noticed shortly after his two-year review that he was losing steam. His work was barely making it in on time, he was less collaborative in meetings, and folks were starting to wonder whether he was on his way out.