David Batson as a psychologist defines altruism as follows: "a motivational state with the ultimate goal of increasing another's welfare."

For him there are two altruisms.

One is the goal of helping others - simple as that.

The other is means altruism where you help others so that you feel happy and fulfilled.

There is no doubt that the latter clearly happens a lot.  We can see that.  It is possible that what we don't see is of that nature too.  Its obvious human nature needs to feel good by helping others.  It is obvious that this is not altruism for it is not about the person who needs something but about how you want to feel.  A feeling is made the prize not the person's wellbeing even though the person will benefit.

True altruism is according to Batson about the first.  In theory, we should have the power to act for the other only.  That does not mean we do have it.

Batson is the author of Altruism in Humans and insists that an altruistic action has to be motivated for if instinct takes over and you react fast that is too automatic to count as altruism or anything else. He says you have altruism and selfishness but the only thing that matters is the quality. Having a good quality motive to help makes you altruistic not the degree to which you are free from selfishness. It is about quality not quantity.

One source of confusion is that if you carry a friend on your back at great personal cost is that if you are not doing this say for a reward from God or even just God's approval and nothing else, their money or praise or whatever you are indeed selfless.  It is about the other not you.  Or is it?  Going through this for nothing is impossible.   You get self-mastery from it.  In fact self-discipline makes you feel free and makes you really free.  It makes you feel safe from many threats.  For example, you can train yourself not to take abuse from others to heart.  It is a better and more long lasting reward than anything else.  Money rots.  It cannot guarantee freedom and it cannot love you back no matter how much you love it.  What gives you fulfillment from it is your mastery over yourself to use it wisely.

Being blunt, no matter how helpful somebody is, they are using you.